Water falls on the 2nd-story floor of from a collapsed ceiling resulting from a flooded roof. Yet in S02E01 when the building needed to be evacuated, it was revealed that the building had a 3rd and 4th floor.
At the end of the first segment Fish is answering the phone while sitting at his desk holding an umbrella to keep the rain off (TRUE) but then at the beginning of the second segment (if the viewer misses the first few seconds after the opening credits, the guys are busy moving the desks in an attempt to avoid the dripping ceiling. Fish's desk was moved, he goes to sit at the end of his desk and picks up his phone which is now not being dripped upon. [sic]
Beckman returns from the roof after inspecting it. His sou'wester hat is wet, but his raincoat doesn't have any moisture on it at all.
When the phone rings, Det. Sgt. Amenguale answers the phone. The ringing continues after he picks up the receiver.