Continuity mistake: Mr. Furlong pushes Zeke into the fishing tank and it breaks, soaking him from head to toe with water. Moments later they are walking out and he is dry.
Continuity mistake: When Zeke is in his car driving and fighting off Miss Burke, just before he crashes into the bus, you see him inside the car struggling to buckle his seat belt and therefore with all hands on it. Problem is, the camera filming the car from the outside clearly shows that the driver has both hands firmly gripped on the steering wheel and is swerving out of control.
Continuity mistake: When Casey is walking up to the school after his father drove him there, we see that Casey's bag strap is backwards. Then they cut to the car, and when they cut back to Casey and all of a sudden, his bagstrap is turned the right way. The next cut is when coach Willis and Casey's father look at Casey and then Casey starts to walk up to the school again and his bag strap is turned backwards again.
Continuity mistake: When Casey is in the closet in the faculty room, the woman teacher, who is talking to the coach, gets water from the water jug and splashes it on her face. The camera cuts to her so you can see her face, but her hair is perfect and there isn't any water anywhere.
Continuity mistake: When Marybeth tells Zeke that he couldn't be sure what he saw when they were all taking the drug-test to see who was an alien, we are shown a flashback of her using a weird extension on her alien finger to cut the blue end of the tube off and let the powder pour away. In the flashback, the blue end falls on the floor and is gone. Yet if you watch the first showing of this scene, when they were actually taking the drug test, we see a very clear shot of Marybeth just after taking the drug, and the blue end of the tube is intact.
Continuity mistake: There's a swimming pool scene, where Stan tells the coach that he doesn't want to play the game. In the start, there's a shot where a kid jumps in the pool, the camera changes and the kid jumps in the pool again.
Continuity mistake: In one scene when Zeke is examining the alien thing under the microscope, he's wearing glasses. He puts them on the back on his head, in the next scene they are back on his nose again, and then suddenly they're back again.
Continuity mistake: In the scene they discover that Delilah is an alien, Casey gets Zeke's gun. Stockely takes the gun from him, and she's holding it one hand, but in the next shot it's in her other hand.
Continuity mistake: When Stokley is pulled into the swimming pool by the alien, you can clearly see that she is bleeding from her mouth. However at the end of the film, when she is in the cage thing, it looks like she has had a nose bleed.
Continuity mistake: When Stan is in the class and the teacher says something about read chapter four, Stan says they are in chapter five, and he puts his arms on the table, but in the next shot, his arms aren't on the table.
Other mistake: After they kill the alien/teacher and leave the school they pass one girl in a blue/green tee-shirt with a waterbottle. Just one scene later you see this girl again under a tree, suddenly in front of them.
Audio problem: When you first see Stokely she says 'crash and burn, Casey' but if you look carefully you notice that her lips don't move with what she is saying.
Continuity mistake: When Stan is taking a shower at school, his soap on a rope is hanging on one side of the shower pipe one minute and the other side the next. Every time you see it, it's hanging on the opposite side that it was in the last shot. This happens four or five times.
Continuity mistake: When Casey and Delilah are in the closet and Nurse Harper is taking a drink from the fridge, from inside the closet you can see Nurse Harper putting the lid back on the drink, but the next scene outside the closet she is again putting the lid on the drink.
Other mistake: When Zeke is examining the alien, he puts his glasses on to look down the microscope, but wears them at no other point in the film. Since microscopes can be focused to the eyes of the user, most scientists take their glasses off to use a microscope.
Continuity mistake: When Stokeley and Casey are chased into the swimming pool area, the alien pulls Stokeley to the floor. You can see a trail of blood from her mouth, then in the next shot the blood has changed into a small neat circle.
Continuity mistake: In the end when the giant alien squirts little aliens into Casey's face, the ones on his right cheek are seen going in twice.
Continuity mistake: When Casey and Stokely are talking in the library, stokely's hair is constantly moving from behind her ear to in front between shots.
Continuity mistake: After Delilah refuses to take the drugs at Zeke's house and runs through the wall, Stokely's sweater keeps changing positions in and out of the house in different perspectives of the camera takes.