Continuity mistake: At the beginning of the movie, the real estate agent greets the McKenzies, lovers of all things open. The potential clients hold the papers in a completely different way at the cut ("I was just telling the Breckins that..." etc). (00:01:15)
Deliberate mistake: When Max knocks out Jeff with a pool ball, he later wakes up with a VR headset on his face, and he is able to see his body and the outfit he is wearing within the VR environment. This is very obviously not how VR works - you are not able to see your own body while in VR, just the environment you're in. This might have been done deliberately so that Jeff was able to see his movements, but it's still a mistake. (01:05:10)