Revealing mistake: At the beginning of the three scoundrels' efforts to retrieve the baby from the cage, Brian Haley manages to lean into the cage so deeply he's in with the whole waist, with enough room for Joe Pantoliano to reach around and helping, even. The setup is so absurd that it is scrapped in the rest of the scene, and Veeko can lean in for a much smaller portion of his body (and still can reach the baby just fine). (00:47:35)
Revealing mistake: Brian Haley's stuntman launches himself out of the building by his own will in the sequence when the cart reaches the edge (he lets go off the cart handle before the impact and jumps right into 'the void'). (01:17:10)
Revealing mistake: In pursuit of the bus, Eddie is turning the van to the left from the main street into an alley. Two different takes have been edited together, as the position of the cars behind and in front of the van changes (not dramatically though, the coordination in the scene has actually been better than much easier scenes). Also you can see on the asphalt obvious skidmarks from previous takes. (00:30:45)
Revealing mistake: When the three criminals jump from one roof to the other to chase the baby, Norby rolls during the landing and ends up against a metal chimney, which gets pushed aside, offering no resistance whatsoever. (00:26:55)
Revealing mistake: In the overhead shot of Eddie flipped back by the plank decking him in the jaw, look when he lands; the modest impact makes a chimney supposedly made of bricks wobble conspicuously. (00:26:05)
Answer: It might have taken a while for them to find the keys to the crane as well as figuring out how to operate it. Once they did, they could get him down.