Look for near the end, when the man with the gun turns left and right, keeping woman and man in check (except that Sara is standing behind Jake).
When Sara enters the library, the camera zooms in on the clock on the wall (it's 11:11). The shadow of the camera can be seen on the wall at the bottom of the screen.
When Sara meets with her professor to request the monitoring equipment, the boom mic casts a noticeable moving shadow on the rows of desks in the background.