During a climatic chase and shootout between Gary Sinise and Kam Heskin's characters inside a high-rise construction site, they take turns running and stopping to exchange gunfire at various locations in the site. However, Kam Heskin almost always seems to stop next to the exact same pillar, which has the initials "DOA" and the word "Keeps" scrawled in graffiti on it.
On the construction site, Mac shelters behind a stack of cinder blocks whilst Suspect X shoots at Mac. Some of Suspect X bullets hit the topmost cinder block and put holes in it. The next camera shot shows Mac and the stack without any bullet holes in the topmost block.
During the chase at the construction site, Suspect X takes cover behind a pillar, and fires her weapon at Mac with one hand. In the following shot, she's out in the open, holding her weapon in both hands.
During the shootout with the assassin, at approximately 38:00 Mac dives behind a stack of concrete blocks. The blocks receive several shots and have a set of bullet holes in them. A second later, Mac pops up from behind the blocks to shoot and there are no bullet holes in the blocks any more.