Goofs

The police dispatcher should have sent another officer to check on the one who was shot after he failed to answer his radio.

When Tom buys 2 bottles of liquor, Mary tells him that the total comes to 11 dollars, but the cash register reads $3.25

James' face is horribly scarred from the fire explained in the movie. However during his last 2 scenes of the movie, his face is shown free of any such scarring.

The shotgun Mary finds is an over-under style where both shells fire separately, but after firing only one shot, both shells are shown to be used and replaced with new ones. Then when the killer grabs the gun in a subsequent scene he fires one shot and discards it, even though it has one shot left. Additionally the gun is referred to as a 'rifle' twice.

Presumably Bobby is American, but the phone number he writes down features some digits written in the European style, i.e. 3, 1, 4, 7, and 9.