Other mistake: Issac is on the phone with his boss and he is holding his phone upside down, noticeable because his otter box case is upside down. (00:14:41)
Continuity mistake: When Isaac and Bob Lee are moving from the stairwell to the office they magically go from not having a sight on their rifle to have a mounted (maybe red dot?) sight on their rifle. (00:17:15)
Continuity mistake: When Bob Lee and Isaac are in the firefight in the office building, the bullet holes in the walls change position or disappear.
