Plot hole: When we first see the reanimated Sparky, his head's sewed on. While that makes him look a bit like the traditional Frankenstein monster, it doesn't make a lot of sense - the original monster had stitches on its neck because it was made from multiple body parts, but it's not like they sawed the dog's head off after it died...
Suggested correction: Do we ever see how much damage the car did?
Plot hole: The whole film is basically told as a flashback from Rand Peltzer's point of view. Now he might be able to talk about things that Billy, his mom, or Kate might have told him, but he wouldn't have known about all the other the gremlins did to the rest of the town like killing Mrs. Deagle, the cops, or the gremlin in the mailbox.
Plot hole: If the underground women really believed that Einstein and Copernicus were female, they wouldn't laugh at the quote of Marie Curie.
Plot hole: Superman (or Kal-El) was a baby when his parents sent him away from Krypton before its destruction, and as Jor-El told his son in his first message he would have already been dead by then for thousands of Superman's years. Kara never existed during any of this yet so somehow she instantly recognizes him from the poster on the wall, even though she should have no idea who he is.
Plot hole: Why would Madison take a bath in steaming hot water? The ocean water is warm or cold depending on the area of the ocean. So, it makes no sense as to why she does this.
Plot hole: When Buckaroo is speaking with the president via video call (with John Parker by Buckaroo's side), New Jersey is explaining the reason humans can't see the aliens from planet 10, is a result of bacteria produced by the aliens which is then absorbed by humans via their olfactory senses, affecting their cerebral cortex. If this is the case, why doesn't the president see John Parker in his true alien persona. He can't smell him through the television. (01:04:50 - 01:05:40)
Plot hole: When Sylvia gets grabbed in her apartment by the bad guys, she's screaming from the get-go and they are standing in front of the door all the time. So Moby should have heard her as he approached the door to ring the doorbell, the door obviously lets sound pass pretty well since he hears her muffled whimpers a few seconds later even being at distance. Somehow, her making noise becomes an issue only once the doorbell has rung and was a non-factor before. (00:43:50)
