Plot hole: When Gwildor tells Julie and Kevin that he can use the Cosmic Key to take them to any point in time they wish, Kevin asks just for them to go straight home. As Kevin and Julie go through the portal, Julie turns around and shouts to Gwildor to send them back before being dragged through the portal completely. When Julie wakes up in bed, she discovers that Gwildor has sent her back to the day her parents were killed. Julie never said where in time she wanted to go, so there's no way Gwildor could know to send her back to the day her parents died.
Plot hole: When Gawain is repairing the hole in the vault wall, a security camera is visible in the top corner in the room.
Plot hole: Cindy manages to pick Crisp out of a line-up even though she was hidden in a box and didn't see him, she only heard his voice. But even with that, he isn't asked to speak during the line-up.
Plot hole: In the opening of the film, some of the characters are flipping through a scrapbook they've made documenting Elle's experiences in the first film. The problem is that many of the pictures are of moments when no photos were taken, so how did they get the pictures to put in the scrapbook?
Plot hole: When the students are breaking into ETS, they take great care to avoid the security cameras in the lobby; donning masks, crawling on the ground, etc. Yet a bit later, two of them go back to guard the same lobby, they are seen walking around and sitting on the desk that they so carefully crawled past earlier.
Plot hole: The Hillbillies take a "short cut" to catch up with the guys after they are taken in by Burt Reynolds. However, the guys get a chance to sleep comfortably until morning before being confronted by them. (01:12:10)
Plot hole: It takes less than 3 minutes to fill the house with water using a mere garden hose? I mean come on...
Plot hole: Michael McKean quits pursuing Beldar and approximately 15 years pass as indicated by Connie growing up, yet when you see McKean again and his assistant, they have not aged at all.
Plot hole: While planting the suicide gear in the bathroom before Buckley comes in, Cooper tells Josh to tie the rope into a noose as they go to hide in the shower. Josh replies that he doesn't even know how to tie a noose. He must be a quick study, because in the 45 seconds or so that it would have taken Buckley to relieve himself and wash his hands, Josh has tied a perfect noose. (01:03:55)
Plot hole: The policeman survives a frontal crash into the hillbilly's truck at full speed without as much a scratch. (00:24:40)
Plot hole: The kidnappers initially ask for a ransom of $50 million. $20 million in $20s, $20 million in $50s, and $10 million in $10s. This translates to a grand total of 2.4 million bills (pieces of paper, that is) Every bill of American currency is 2.61 inches wide, 6.14 inches long, and .0043 inches thick. This makes roughly 2,791 bills to form a 1 foot tall stack. This means that the 2.4 million bills would take up a space of 96 cubic feet (assuming they are packed as tightly as possible). Also, since 490 bills make 1 pound, the 2.4 million bills would weigh (interestingly enough) just over 2.4 tons. No way they can move it.
Plot hole: Edward Lionheart severs the head of theater critic Horace Sprout while Sprout and his wife are asleep. (Lionheart gave them both a knockout injection). Sprout's wife (and his maid)discover the severed head in the morning, and both scream and faint. But in the next scene, critic Perry Devlin retrieves his morning newspaper and then reaches for his bottle of milk, only to find Sprout's head perched on the milk bottle. How did the head get from Sprout's house to Devlin's place?
Plot hole: The fact that David becomes conscious after being hit and left back is dramatically fine but there is no aftermath - he misses to finish dealing with Ali and friends at that point.
Plot hole: When Hugh is walking near the park gate, he should have seen Marcus. Marcus was on the same side of the post as Will was.
Plot hole: With people around the world turned into zombies, there is no way to maintain power plants, thus no lights should be lit, not to mention the functionality of an amusement park.
Suggested correction: The sequel film gives this a (very flimsy) justification, saying that everything runs on power from dams. Stupid, but at least trying to explain things.
Plot hole: At the end of the film the boss says that he and Miss Fitzgerald are going to go on holiday together to Paris (talking about the actual city, not the secret code they have invented). However, the film is set in 1940 and Paris would have been an unusual place to take a holiday at this time, considering France was in the middle of a war... Pretty dangerous for civilians even though America was still neutral at the time.