Revealing mistake: After her brother's death, there is a scene in which Alice starts practicing with her brother's nun-chuks. They never show the real actress doing the tricks; instead, they cut to an angle from behind her and show a double who has darker, shorter hair than the real actress and is a bit bigger.
Continuity mistake: At Rick's funeral, Debbie gives Alice her spike bracelet. The spikes are flat and there aren't that many of them, but at the end when Alice is getting decked out to fight Freddy she pulls the bracelet out of her drawer, and the spikes are very menacing looking and there are more of them.
Continuity mistake: When Dan is wheeled into the operating room, we hear a respirator machine going in the background. Yet he's fully awake and not hooked up to any breathing equipment when he's being brought in. A machine would not be going like that unless the patient was fully under and intubated.