In the last confrontation Nancy has with Freddy, you see her pushing him down the stairs. Yet if you look closely you can see the mattress that the "Stunt" Freddy falls on.
Nancy sets up the sledgehammer booby trap and runs down the stairs. Freddy opens the door in pursuit of her, setting off the trap, and the impact of the sledgehammer causes him to stumble and fall over the railing. This is where you see Freddy land comfortably on a very obvious stunt mattress.
In the scene where Nancy is running up the stairs away from Freddy, you can see the place on the steps that is going to turn to goo under her feet before she steps on it.
When Nancy checks the time on her watch, she's wearing a sweater you don't see when the camera shows the wide view
Contributed by: Steven Murray
If you look carefully when Tina (Amanda Wyss) is first slashed by Freddy's claws on her torso, you can see as the blood starts to pour out, and Amanda pulls her hands up to stop it, her arm catches on the prosthetic and pulls it up slightly at the bottom left corner of the screen.
Contributed by: Adam Juhl
After Freddy catches fire you can hear a fire extinguisher while Nancy is at the front door.
Contributed by: david shalkowski
When Nancy is looking for Freddy in her final nightmare, Freddy is seen for an instant wearing his hat after Nancy pulled it off his head during her nightmare at the dream clinic.