Other mistake: The red Dodge Charger plows through a locked metal gate as they are going to make the bust on the meth lab. Moments later, you see the front on the shiny red Charger, and there is not a hint of a scratch on the paint, despite going head on through a locked metal gate moments before. (00:06:55)Quantom X
Continuity mistake: Roy picks up the solid gold cross in the house and throws it onto his shoulder, Roy is a big man and he struggles to do this due to the size and weight, but near the end of the film the same gold cross is handed to Hayes and there appears to be no weight to it - also it is considerably smaller.
Continuity mistake: When Nick and Hayes are fighting, and the time leading up to it, the Soul gun is using limited ammunition, but earlier in the movie when Nick was shooting up a building to hit Polaski he fires more shots and does not reload or run out. (01:20:00 - 01:20:50)