Goofs

Chase is seen taking white wall tires off a wrecked car and putting them on his own. In the next scene, he has black wall tires on his car. The white wall tires change back and forth several times from scene to scene after that. (additional info) During the making of the film, several times Chase's car broke an axle. It was common for this car because of its high speed. Also due to rough country roads. This may be why the frequent tire changes noticed in the movie.

The locomotive pulling the train that crashes off the bridge knocked down by the title creature, changes from a switch engine to a streamlined unit, then back to the switch engine, but pulling in reverse and then back to a head-on view of the streamliner, just before the crash.

At 18:56 the lighting changes from dark to dusk, when Chase is driving away from the first wreck. As he gets to the suitcase on the side of the road, it changes back to darkness.

The attack on the hitchhiker takes place on a road through dense woods, but the obviously blown-up shots of the gila monster are against a clear sky background on a rock, not a tree in sight.

Someone has mentioned the railroad loco continuity. There seem to three different locos depicted - a streamline Cotton Belt loco, a smaller diesel then the model loco looks smaller again - like a switcher.

The disc jockey in the barn jokingly refers to " Bangkok, Siam " . Siam changed its name to Thailand in 1948 - 11 years prior to the film.

The string pulling at the back of the oil truck is visible in the shot when it crashes.

As the freight train crashes, you can plainly see the string pulling the engine off the tracks. Once it goes off, the rest of the train follows.

The scene in the Barn during the party, as the Giant Gila Monster breaks through the window is a bit disjointed. Everyone looks straight ahead toward the camera as the monster breaks in. But Old Man Harris in the background, watches as the Gila Monster coming in through the window, is looking confused. Everybody runs out to the left to escape, but Old Man Harris runs up the stairs. Everybody ends up outside through the big barn doors. But Old Man Harris is no where to be seen. This is due to a cut scene. Old Man Harris's death scene which was cut from the movie or never filmed.

Just before the train crash, there's a shot of Shug Fisher, playing Old Man Harris, in his car, reacting to the sight of the Giant Gila Monster. Reflected in the windshield is director Ray Kellogg giving Fisher the cue to turn his head.

At 21 minutes into the movie, right after Chase and the Sheriff find the suitcase in the road. When Chase begins to drive off you will see the lamp that lights up the scene. It will be moving on the right.

Just after Chase receives the phone call from the Sheriff about the wrecked oil truck, in the next scene the shadow of the boom mic can be seen in the lower left corner of the frame, next to the police car, right before Chase pulls up in his dragster.

Referring to causes for dwarfism and gigantism, the Sheriff cites "the pituitory gland," instead of the proper "pituitary."