Other mistake: During the quake, we see the furniture, wall panels, ceiling tile, windowpanes, vertical blinds, etc., in the office fall, shake, or crack. Yet the leaves of a large potted plant do not move at all.
Other mistake: Outside of the office building, Stewart and Remy take shelter under a vehicle, despite falling debris crushing vehicles in their midst.
Answer: There are two versions of the film. A 'film' version which does not include this scene (and others) and a 'TV Miniseries' version. The miniseries version was made to run over two nights and extra scenes were shot to extend the running time.
jle