(at around 1h 22 mins) When Alice is fighting Freddy in the church Freddy says "I...am...eternal" But it is obvious that he says something else (looks like "forever") because his lips movement doesn't match the word.
In the previous film 'A Nightmare On Elm Street 3: Dream Warriors, Freddy had carved the message "COME AND GET HIM BITCH" on Joey's chest. The cuts in his chest were deep enough to have left permanent scars. In the beginning of this movie Joey is shown with his shirt off in his water bed, but he has no scars on his chest.
(at around 1h 7 mins) When Alice sneaks out at night to meet Dan at the diner, she grabs a pair of white tennis shoes before she runs out (and you can see her wearing them when she runs around the corner of the diner). A little while later (at around 1h 12 mins), when Alice attempts to run over Freddy with Dan's truck, the foot stepping on the gas is wearing a brown boot with red laces.
(at around 7 mins) In the beginning when Kristen is driving to Alice's house, the crew and some onlookers are clearly visible at the end of the street. They can be seen just below the rear-view mirror.
Just after Alice and Dan crash the truck into the tree (when they think they are going to crash into/hit Freddy), you see Alice lean over to look at Dan, who is unconscious. If you look at the area of Dan's right shoulder, you can clearly see the reflection of a man wearing a white t-shirt, presumably a crew member, in the truck's window moving around.
(at around 1h 21 mins) When Alice is fighting Freddy in the church, she burns a hole through his body. Not only is it obvious that the hole isn't actually there but it is a cartoon effect superimposed over Freddy but when the camera goes away and then comes back, there is a panel of brightness at the top left hand corner of the effect so you can't see the Freddy jumper clearly.
(at around 20 mins) After Freddy stabs Kincaid in the dream world, he awakens and grabs his stomach but there is no blood. But later when Kristen and Joey are killed, there is physical evidence in the real world of how they met their fate.