Continuity mistake: After Nancy pulls her phone out in frustration, she wraps the phone cord around it, and places it on her bed nice and neatly. But in the next shot of the phone mysteriously ringing, the phone is in a different position and the phone cord is wrapped around the phone differently.
Revealing mistake: Near the beginning, during Tina's first dream, Tina gets cornered in front of one of the furnaces. She steps forward and Freddy jumps out from behind her and scares her. When she steps forward, Freddy (who is trying to lean down out of the shot) is seen stepping sideways to position himself to scare Tina.
Continuity mistake: When Nancy is at her bedroom window, she says "OK Krueger, we play in your court" and she is holding her alarm clock. She then pulls down the blind, then when it cuts to inside, Nancy is walking over to her bed but isn't holding her alarm clock. If you look, the clock is on her bedside table, but she doesn't put it there.
Visible crew/equipment: When Nancy "jumps" from the boiler room to her front garden you can see her land in a pile of bushes. You don't even have to look closely to see the big black air mattress she lands on. It actually bounces above the fake bushes and becomes almost completely visible.
Continuity mistake: When Nancy is in the boiler room towards the end of the movie, Freddy suddenly jumps out and scares her. In this shot Freddy is wearing his hat. Earlier in the movie Nancy took the hat from him. After the shot where Freddy jumps out at her with his hat on, the next scene shows him chasing her down a staircase without his hat.
Plot hole: Following Glen's death, Nancy tells her father to come across the street in 20 minutes to catch Freddy. She then goes to her house, checks and sets her alarm clock, and proceeds to rig the ENTIRE house with booby traps, including filling a light bulb with the contents of several shotgun shells, and has a heart-to-heart talk with her inebriated mom. When she gets back to her room to go to sleep, she checks her clock again. The time on the clock has advanced only TEN minutes. She did ALL that in only TEN minutes?
Visible crew/equipment: This is during the part where the girl dies in the bedroom with her boyfriend (where she gets dragged up along the roof). Just before, when you see the marks made by Freddy's glove, and her hands come up to show her pain, she clearly grabs a chunk of the thin latex pad (best viewed in slo-mo).