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: 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 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)
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: 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: 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)
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: When Marisa tries to save the hero by telling an old lady to move her car, the window is all the way down looking in, an inch raised looking out. (01:23:05)
Continuity mistake: The gatekeeper lets Marisa and David in; the position of his clipboard changes between shots, and so does the position of the other hand, quite more noticeably so since it's off the button column, then on it suddenly again. (01:17:50)
Visible crew/equipment: The vindictive alligator demolishes the bad guy's car; in the shot where the tyre flies off, you can spot the jack under the car. (01:17:05)
Continuity mistake: At the beginning of the party, Mr. Slade has a bunch of steak on the grill, but just two of them when he turns towards the mayor with an angry face. (01:14:30)
Character mistake: When Marisa leaves the diner, you can see the door has a "Push" tag. However, the door opens inwards, and in fact to go outside she has to pull. (01:08:00)
Other mistake: When Henry Silva is trapped in the jaws of the animal and screams asking for help from his indigenous sidekick, the beast is hardly crushing his body, more like holding it in place with no damage to his clothes or blood, and then turns it around between shots. (01:06:00)
Other mistake: The alligator baits Col. Brock through a feat of chinese shadow puppetry certainly quite unlikely for the intelligence shown in the rest of the movie, and inconsistent with the movements he's capable of, not to mention the fact that he would have needed to perfectly abscond covering himself in trash bags super-fast, flawlessly, silently. (01:05:00)
Continuity mistake: When Marisa Kendall talks with her obviously arteriosclerotic mother on the phone, she holds the receiver in different ways between shots. (00:59:45)
Revealing mistake: After the unmissable scene of a very excited Henry Silva appraising alligator dung, there's a small intermission showing some news on the TV. The "tv" is a literal cutout of a television that frames the footage. It's not even cut properly, the lines are jagged and not smooth. (00:52:50)
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)
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)
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)
