Continuity mistake: At the end, during the fighting in the Cathedral, the last woman left is getting first cut by Steven Seagal at the right breast. A moment later, her cut is on her left side. The next moment it is on the right side again.
Deliberate mistake: Throughout the movie, Seagal's voice changes. In some scenes, his lines are spoken by someone else (with a much coarser voice) and dubbed in, which is confirmed by numerous sources over the internet.
Audio problem: Throughout the film, no matter who is using the blade weapon that attaches to the wrists, like the one given to Steven Seagal at the arsenal scene, the sound when used is like a metallic sounding blade instead of the carbon or graphite blades.
Revealing mistake: They let us see the stunt double's face for the girl Steven Seagal is fighting in the ending Cathedral scene, and she looks nothing like the actress.