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: Although it is explained how the chipmunks were able to get away with the balloon race by tricking Ms. Miller, wouldn't Ms. Miller know that the chipettes were in on the balloon race? Especially considering the fact that she is their guardian? Also, why would she offer to babysit the chipmunks if she has chipettes to look after herself? Despite this, the chipettes were never brought along to Dave's house with Ms. Miller. And what is Ms. Miller still doing in Dave's house if she thinks the chipmunks are with Dave? Unless maybe she's taking care of the house...
Plot hole: The army showing up at the end of the movie is wrong on numerous levels. 1) Eugene wrote and sent out the letter that day. I find it hard to believe the mailed letter got to the army in just a few hours time. 2) How did the army know to show up at time square? When Eugene wrote the letter, nowhere did it say where to meet. Plus the boys didn't decide to go to time square until the last minute. 3) since when is the army deployed to battle monsters based on a letter that was written by a child?
Suggested correction: The army's arrival being unrealistic is a very deliberate joke, like the armadillo-rats from earlier in the movie.
I submitted a category change to "Factual Error" to help cover this. It is indeed too deliberate to be a true plothole, but it is nonetheless amusing to point out all the ridiculous ways this humorous scene defies believability.
Plot hole: In the scene where Westley is tortured to extremity, he screams, and upon hearing him scream, Inigo is instantly able to identify Westley and that he is in love with someone about to marry. You could say Fezzik told him, but how did Fezzik know? For all they knew, he was just a pirate after a prize.
Plot hole: It's brought up several times that the kind of music Cronauer is playing is not acceptable. Then why would such records of those songs be at the radio station in the first place?
Plot hole: After the car burns, and they arrive at the motel, Neal only has $17.00 on him and nothing but melted credit cards, forcing him to give up his watch to help pay for the room. Del only has $2.00 but his watch doesn't quite flip the bill. At this point, between Neal and Del, they only have $2.00. However, when Neal invites Del into the room, so he doesn't freeze to death, they are eating Doritos and drinking shooters. Even in 1987 Doritos and a bunch of shooters must have cost more than $2.00. This is assuming Del didn't already have them in his trunk. But even if he did, at the end, Neal gets on his train, makes a return trip to find Del just where he thought he'd be, and then they'd both have to get back onto that train. After all, they both showed up at Neal's home. Once again, It would take money to get on that train. Four train fares with only $2.00. Neal's first trip, return trip, and Neal with Del for the last trip = four fares.
Plot hole: The fact that Buddy placed the knife and note in the steering wheel of Jerry's car is unrealistic. Buddy first met Jerry in the bathroom after school started and Jerry hasn't gone outside of the school building to his car until this point later in the morning... so there's no way that Buddy could have known which car was Jerry's to pull this stunt.