Continuity mistake: When Lisa's mother turns off the light you see two guys wearing blue shirts standing outside. When they see the light turns off they turn around. When it cuts they turn around again. (00:50:00)
Continuity mistake: When Jessie sits on the ground after being hit by the baseball you see him about to get up. Then Schneider approaches him and when it cuts you see Jessie sitting still. (00:08:50)
Visible crew/equipment: When the balls are all bouncing of their shelves, there is one closeup of three balls, one basketball that bounces off, then two white footballs which roll off the shelf. You can clearly see a wire attached to one of the footballs. (00:33:50)
Other mistake: If Freddy ripped his scalp off, it would be his skull, not his bare brain. It's not like he pulled both of them off at once. Freddy's got a skull, as we saw when Tina took his face off in the first film, so why is the top of it missing in this one?
Suggested correction: This scene takes place within Jesse's nightmare, which is Freddy's domain, so Freddy can manipulate any detail he wants, in this case, exposing his brain without cutting open his skull.