If Mark jumped off the side of the pier, where he knocked the MP through the railing, he could escape into the sea before he's caught.

Why on earth does Schubert think the bracelet will work on Mark when it already failed to control him twice?

Mark may destroy the underwater complex, but he doesn't rescue those poor whales.

Those fingers of Mark's sure don't look webbed when he says good-bye to Elizabeth.

The Death Scouts

The aliens move in a very stiff and unnatural way, except when Lioa is first seen exiting the sea; then she smoothes back her hair twice in a very human gesture.

If those so-called wetsuits are really the alins' skin, then does that mean Xos and Lioa are naked?

When Elizabeth announces that the stone is radioactive, no one seems to be overly concerned that it might be harmful.

The aliens' and Mark's hair is instantly dry immediately after leaving the water several times during this episode.

Lioa says that they are, in their true form, small creatures. Then what was it that pulled the three divers overboard?

For some reason, the entire climax to this episode is shot in slow motion.

The diving hatch on the Cetacean is shown closing just when it should be opening to let Mark inside.

Killer Spores

While under alien control, Mark states that the mysterious bubbles are still there because "they have to be." We never learn the significance of those bubbles.

While on the Cetacean, Elizabeth and Miller know the sub is contaminated with something, yet they return to the lab. Then they seem shocked when Mark reveals that the spores are leaving to contaminate the rest of the world. It would've been much safer to stay submerged; at least there would be a chance of containing the aliens.

When Miller uses a simple squirt bottle, it somehow makes an aerosol sound.

Elizabeth and Miller question whether the footprints in the sand might be Mark's. Are there any other footptints leading from his car into the desert?

The helicopter arrives with only one medic aboard. What if Miller hadn't been there to help carry the stretcher?

A traffic cop firing six rounds into the air doesn't even phase the pedestrian in the crosswalk behind him. I'd be running for cover!

"What's the matter?" Elizabeth asks Mark when he cringes and covers his ears for the third time this episode. Probably the same thing that was wrong the other times: the spores' voices are hurting his ears.

Alone on the sea bottom, Mark remembers a conversation between himself and his scientist friends. Only there's no place in the episode when that conversation could have taken place.

C.W. says that the Foundation is a secret organization. Secret? With a sign out front?

When humans are controlled by the spores, they behave like zombies, doing only what the aliens make them do. So the spores must've ordered Elizabeth to put her hair up.

When Mark takes off for the rocket, he must be carrying all the spores. Except for the one inhabiting C.W., as we see the Foundation's coordinator obviously still under alien control. C.W. soon meets Mark on the beach, and you'd think he would transfer the spore then. But, no, C.W.'s face is no longer gray, and he acts like he's normal again. Perhaps the spore simply left C.W. and travelled to Mark under its own power. Which brings up an interesting question: why do the spores need Mark to bring them to the rocket launch? Are they so slow that he can swim faster than they can fly?

Did Mark close the door on the capsule before launch?

Mark has a mere four hours to get the spores to the launch site. Even though the Cetacean is travelling at maximum speed, he exits and makes a swim for it. Obviously, the man from Atlantis is faster on his own than even this advanced submarine. Mark is then taken by helicopter to the rocket base, where he dashes up innumerable flights of stairs and transfers the spores to the capsule just in the nick of time. When Mark returns to Mission Control, Elizabeth is there. So, she travelled by sub and then somehow from the shore to the base, and was not at all far behind Mark.

We understand why Mark is not rendered comatose when the spores leave him; his physiology is markedly different than humans. But why is the crew of the Cetacean unaffected after being possessed?

The Disappearances

Why is Jane so surprised when Mark says he works underwater? Any ordinary diver would've given the same answer.

What's up with Elizabeth driving on the wrong wide of the road?

The palm-reading machine works without Mark inserting a coin. The previous customer must've left without getting her money's worth.

Maybe Elizabeth should've tried diving into the water to escape from Stoneman; at least it would've given her a chance.

Elizabeth claims that Mark will die if left in the shed, as his "medical condition" must be treated every four hours. Yet, when C.W. and Miller arrive after an all-night search, Mark is still alive, albeit, barely.

You can see the wires holding up the Cetacean when it turns.

When the torpedo attaches itself to the hull of the Cetacean, C.W. suggests calling in the Navy, but his idea is quickly scotched by Miller. If there's a chance that the entire crew will die, then they should call the Navy; at least someone will know the criminals' whereabouts.

The torpedo passes out of the Cetacean's camera view when it connects with the hull. But the cameras are able to watch while Mark tampers with the explosive.

Why do the guards walk around shirtless all the time? For Dr. Smith's personal gratification?

Dr. Smith claims that Mark was left for dead twice that she knows of, though we only see it happen once.

The guards may be obedient due to the properties of the water, but the sure aren't slap-happy like the scientists.

Melt Down

Somewhere between leaving the bridge and entering the elevator, Mark loses his shoes.

Does Mark always carry a test tube in his swim trunks? He left the Cetacean to search for a current, not collect specimens.

Just how does carrying that little conducer protect you from radiation?

The Mudworm

We hear Jane say that the Cetacean's camera is at maximum magnification. A moment later, it switches to a much closer view of the Mud Worm.

Jane says the torpedo is pointed straight at them when the camera's view shows it aimed 90 degrees to the right.

Although the title of the episode lists "Mudworm" as one word, the label on Schubert's control panel clearly makes it two. And he ought to know.

The Hawk of Mu

Mark can see in the dark; otherwise he couldn't navigate at the bottom of the ocean. So why does he light those torches?

Claiming to have read about Mata Hari and to understand such things, Mark asks Juliette if she is trying to seduce him. Yet earlier, when Schubert's pretty hireling tried to vamp him, Mark was utterly clueless.

Giant

Instead of asking Thark to turn off his sluice, Mark should get him to channel the water back into our world when he's finished with it. Where does all that water go, anyway? Even an invisible lake should turn that desert a bit more hospitable.

It's odd enough that the sluice disappears when it's shut off, but why should the well vanish, too? And how does Thark know it will? Weird.

Muldoon laments that this world he's trapped in has no people. But Thark said earlier that, though he mines, others do other things. Presumably, Muldoon will find out about these others sooner or later.

Man o' War

In this episode we get a good look at the face of Mark's stunt double, normally seen only from the back.

When Mark leads the raid on Schubert's house, Poobah's huge tank and the tunnel that connects it to the sea are both gone, only to return later when the coast is clear. But we are never told how Schubert managed to accomplish this.

Mark reveals the power to summon sea creatures, override electronic signals, and disrupt an automated sprinkler system with his voice. Why doesn't he ever use this fantastic ability again?

Shoot-Out at Land's End

Mark rides a horse very well for someone who doesn't know the first thing about it.

In the heat of a tense moment, Billy calls Mark "Billy-boy."

Crystal Water, Sudden Death

Mark is wearing his sunglasses when he heads for the Cetacean, but not when he enters the bridge. There he picks up his glasses from the console.

The wires are visible on the Cetacean.

As the Cetacean passes through the break in the reef, clearance is only two-and-a-half feet on either side. And Jomo spares a glance at Chuey while he's steering through this dangerous crevice.

Why did Mark even bring his sunglasses on his swim to the force field? Did he expect to find an air-breathing civilization inside?

The communications officer complains that there is too much interference to contact Mark. Just how did she plan to communicate with him? Is he wearing some device that we can't see, hidden somewhere on his person?

Mark sticks his sunglasses inside his swim trunks at times, but the bulge is not visible.

Schubert still has one crystal, the one Mark inserted into his communications dish.

Mark frightens the villains into leaving the crystals, making them think their submarine is gone and they have no escape if the force field dome collapses. Then what? Does Mark arrest them all by his lonesome? Eventually, they'll return to the sea and find their sub intact. What's to stop them from coming right back for the crystals?

The Naked Montague

C.W. Hyde

Mark has no way of knowing whose room key that is. So why the snarky expression?

Scavenger Hunt

Muldoon says that his pet Oscar is able to open a portal between worlds by himself. He later shows Mark the portal, which exists before they convince Oscar to go back to his own world. Apparently, when Oscar creates a portal, it stays there. So, Muldoon should be able to return through the portal, even without Oscar's help, whenever he chooses. He might even pick up some gold nuggets while he's on the other side.

Imp

That gauge on the wall should indicate the rising water level in the diving room. But when we see inside, the room isn't filling up with water at all.

Mark enters the sea base Triton 1 and meets Duke. When Elizabeth contacts him and asks about the rest of the crew, the Atlantean says they do not appear to be there, without ever checking the other parts of the base.

In some shots, Duke has a strap between his legs, securing his scuba tank, though it is missing in others.

Nobody worries about Duke getting the bends from diving at a depth that supposedly only Mark can reach.

When Mark pulls an injured Duke from the water, Elizabeth...the doctor...doesn't move a muscle. In fact, two bystanders rush past her to help as she agrees to call an ambulance.

Elizabeth calls to Mark to keep an eye on Moby, but the man from Atlantis simply watches the imp dash out of sight without even trying to follow.

The Siren

The radar blip suddenly appears after Mark's been hanging out next to the enemy sub for some minutes.

Mark asks the Cetacean to send him the "surface-to-airlock transport," an awfully fancy name for a scuba tank.

Deadly Carnival

that electrical box outside the museum is sure easy prey to vandals and would-be criminals, even those without an electric limb.

If Mark can turn off the breaker switches to the museum's interior alarms, couldn't he turn off the alarms in the Egyptian display just as well?

The microscopic filaments are supposed to be embedded in the glass case, but they move when the case is moved, as if they're just hanging there.