Part of The Empire State Building was built in the CBS Radford Studios.
The car in long term storage, a Ford Thunderbird, has an emblem on it: an M over a T. It looks like a car company logo but it actually stands for "Mac Taylor".
This being the 100th episode, it's a not-so-subtle coincidence the episode begins with a man descending stairs desperately trying to exit the stairwell on floor 100.
The home DVD release includes a special titled "Celebrating 100: Evidence of a Hit" following the episode.