When John searches downstairs, he's wearing stage make-up and his silver jacket. When he goes upstairs, he's clean-faced and wearing a sweater. Then when he goes back downstairs, he's wearing the make-up and jacket again.
When the group is drinking in two shots that are shown their positions obviously don't match.
When woman comes to a band member's room and talks to him and he falls asleep, his position changes in two shots showing him sleeping.
When the band is playing a song, there is no head on Triton's guitar.
No blood shown when demon bites off a part of victim's hand thus revealing a fake body part..
When the girl is playing the synthesizer, it's not even featured in the song when she is playing it.
Although there is snow around Triton when he is driving the van, there is no snow around the place they are staying.
When camera is going around the house at the start of the movie, a cameraman can be seen in the reflection of the stairs when camera goes upstairs.