I don't know how athletic you two are, but Bill Murray was doing push-ups, not sit-ups.
16 of 6577 found this helpful. Did you?
Nick Krukowski writes:
That's because he is moving while doing the sit-ups, making the money move
15 of 6576 found this helpful. Did you?
Flambore writes:
Nope-
Russell only threw the money on him after he finished the situps. The cuts between him and Bill Murray were just dialog while he was laying on the floor. I was gonna post this one, but someone beat me to it. It's probably the most obvious one in the movie.