When J.P. is sawing the wood, you can see that there are no teeth on the saw blade. Also, the sound of the saw cutting is not in sync with the motion. It is an obvious and significant discrepancy.
When JP meet Nora at her empty camp, you can see a strange shadow on the campfire who resemble exactly as a camera on his tripod.
When JP go out at one moment of the movie, you can see exit the lighthouse and passing in front of the porch. You can see in the reflection of a windows, crew members and the boom mic.