When Lazerov kills the drug dealer in the opening scene, he doesn't even use the revolver they plant as the murder weapon to kill him, he uses his police issued 9mm. an unfired gun with a different type bullet would obviously reveal foul play.
In the first scene at Ashford's apartment Pollack exits into a hallway, onto an elevator (and goes down) while Ashford dances. In the second scene at the apartment Pollack is pushed out of the door onto a rainy sidewalk.
At 1:11:13 a gunshot is fired which sounds silenced, at 1:11:15 the gun which fires the shot is shown with no silencer and the slide of the gun is shown locked open as if its the last shot in the magazine, then at 1:11:17 the same gun is shown again with the slide closed back in its normal position without any noise or character interaction.
Pollack makes a Xerox copy in the archive:
He folds back the file and puts it on the exposure glass.
He leaves the top cover open, he keeps down the booklet by hand and he starts copying.
At the next moment we can see the booklet unfolded and pressed down by the closed top cover.