Plot hole: When the policeman asks Kirsty at the beginning who came when she solved the box she says the Cenobites; she had no way of knowing what they were called. Frank only told Julia; Kirsty didn't hear it anywhere and the Cenobites themselves didn't tell her either.
Plot hole: After Dennis (the first guard assistant) gets killed, the vault is open for several minutes before the old guard arrives. The hobgoblins, however, do not run for their freedom, but patiently wait until the hero, Kevin, comes in a later scene and opens the door. Then they escape as quickly as they can.
Plot hole: Freddy is killed at the end because he sees his own reflection in a mirror, which causes the souls in his body to revolt and kill him. But this weakness to mirrors and reflections doesn't fit in any other film of the series. He repeatedly appears in mirrors in the other films, and in the climax of "Dream Warriors," he even appears in a hallway of mirrors that are facing each other, where he would have seen his own reflection multiple times. No matter how you slice it, his death in this movie doesn't add up in the overall context of the series.
