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: Billy's not tall enough to impale Linnea Quigley on deer antlers.
Suggested correction: The movie blatantly shows Billy lifting her high enough above his head to impale her. It's literally right there in the scene. Additionally Linnea Quigley talks about the making of the scene in the documentary "In Search of Darkness Part II," and talks about the actor living her high above his head over and over while making the scene.