The boombox Lance Henrickson's metalhead son Scott is listening to has a cassette in it by Al Green (unlikely enough), but the music playing from it is by New Wave band Gleaming Spires.
When Bonnie is taking a shower, an overhead shot shows that she has rinsed all of the lather out of her hair. However, the next shot from outside the shower curtain shows her with lather still in her hair.
Lance Henriksen's partner get both his arms severed, but you can clearly make out his arms underneath his shirt.
Steadicam reflected in the mirror when Lucas is searching his house in opening sequence.
Lighting equipment visible on the far left side of the frame during exterior night shot of the house.