Visible crew/equipment: In the opening shot of the movie, several people (presumably the film crew) are reflected in the eye of the titular reptile. (00:00:15)
Continuity mistake: David asks for advice to the store owner. The man points at him with his hand turned in a different way between shots. (00:05:15)
Continuity mistake: David helps the coroner put away in the large plastic bag a chewed human arm. A policeman calls him; he places his right hand flat on the railing, gripping it, but in the reverse shot he's leaning the closed fist on it, and tilted at an angle. (00:05:55)
Continuity mistake: Luke Gutchel is at the evil pharmaceutical company. The scientist tells him he wants 'puppies'; it cuts away on him a moment, and the garbage bag has changed position on the cart. (00:08:25)
Revealing mistake: Gutchel brings in the sewers the animal carcasses using the supermarket cart. He gets inside, then passes a first tunnel, then another one...or rather, passes the exact same tunnel as before, but in the other direction, to make it look like he travelled a bigger length - just check the graffiti on the wall, it's the same one. (00:09:25)
Continuity mistake: When the boss of the laboratory sits on the desk, he moves just the lamp, but the board has moved next to the lighter as well. (00:13:55)
Revealing mistake: After the press conference, there's a close-up of a newspaper ("The National Probe") which features obvious repetition of the same paragraphs over and over. (00:16:55)
Continuity mistake: In the scene with the crazy guy and his exploding breast apparatus, the shirt and the position of his hands and the bomb keep changing depending on the camera angle. (00:18:25)
Continuity mistake: The rookie holds at gunpoint the Mad Bomber; in close-up John Lisbon Wood's shoulder is bare, but in the wider angles the shirt is still up and the collar is in place. (00:19:20)
Continuity mistake: In his first trip in the sewers, Madison picks a brick; in close-up at the beginning Officer Jim Kelly has the flashlight pointed up. David drops the brick in the water; Kelly stepped forward and the flashlight is pointed down. Back to the original camera angle, and he's back holding the torch up. (00:22:35)
Continuity mistake: When Kelly grabs his coworker's butt, he does it with the left hand in the Jaws-like POV, but then it turns out he's using the right hand and the left hand is the one holding the flashlight. (00:25:00)
Continuity mistake: David's boss is driving him after the visit to the herpetologist. In the middle of the conversation the passenger's window goes from all the way up to halfway open and back to closed again. (00:30:50)
Continuity mistake: When the slimeball reporter is listening to an all-too-chatty nurse, he is leaning against his own hand which is in a different position in the reverse shot. (00:32:20)
Continuity mistake: David is looking at the book about alligators; he holds it with the fingers at the top corner, but in the reverse shot the fingers are not visible in that spot. (00:35:00)
Other mistake: David is trying to locate the beast through a map of the city - for some reason, since he already located it before. Problem is, the movie is set in Missouri but the map he's looking at on his bed is a map of Los Angeles (you can even read "Granada Hills"). Similar mistake a few minutes later in front of the sewers; you can easily read "Monterey Park" to the right of a different map he props against the wall. (00:37:15 - 00:38:35)
Revealing mistake: Obvious B-movie special effect when the alligator breaks through the sidewalk, supposedly creating earthquake-like tremors that are simply someone shaking the camera up and down and the cement bends and deforms like cardboard. (00:44:00)
Revealing mistake: A policeman hilariously crashes his car because he was coming in too fast when the kids escaped the molegator. The car that explodes has square, all red emergency lights, but the car that was speeding through the street had red and blue lights of a different shape. (00:44:50)
Continuity mistake: When the kid tries to pry the phone off his drunk mother's hands before leaving to challenge it to a knife fight, the hand position on the cord changes between shots. (00:46:00)
Continuity mistake: After the large mudprint of "Ramon" has been found, David has to make his way back from the lake through a crowd of street vendors and weirdos in general spurred by the presence of the big animal. Just before he meets a bald guy that is carting several plush crocodiles, there's some young fella in a blue and red checkered shirt. David walks past this group and in the next shot after a while he runs in the shirt guy again. (00:49:25)
Continuity mistake: A guy tries to sell a baby alligator to the protagonist. He approaches it holding the lid of the shoebox in his right hand, but in the reverse shot he's holding it in the left hand. (00:49:40)
