Corrected entry: When they are being chased in Madison Square Garden, Nick knocks over a rack of balls and a gumball machine. They show the dinosaurs slipping and sliding. Nick then runs down stairs and joins the others. Shortly, they turn around and see the dinosaurs slipping and sliding on the balls again even though they're now one level lower.
mrfrede
17th May 2013
Correction: Nick actually knocked the balls and gumball machine over that are actually close to the stairs that Nick then runs down. The balls and gumballs simply continued to bounce and roll down the stairs down to the lower level.