Other mistake: When Cindy is watching the tape for the first time and we look up the cellar stairs there are some coats hanging to the left. Later in the movie when Cindy is in the cellar she recognizes the stairs and realises she is in Tabitha's old family house. The same coats are still hanging there, in exactly the same places. Wouldn't Tom have thrown all the old stuff that belonged to Tabitha's family when he moved in?
Other mistake: When we first get to see Tom's house it is that there is nothing else than a corn field on the left side of the entrance to the house. Later when we see Tom running out of the house looking for Sue, trees and bushes suddenly appears on the left side instead of the corn field. Also the above shot of the house property later doesn't match what we've seen earlier.
Other mistake: When Cindy slides the knife under the door she says that the aliens are hideous and gives a description of what they look like. When Mahalik comes crashing into the basement, George says, "There's two of them at the door." Cindy never said how many were there she just said what they looked like so George couldn't have known how many aliens were at the door.