Did the Italian job bus go over the cliff edge?

It is unknown if it did or didn't. The film makers left the Italian job with the 'cliffhanger' (pardon the pun), which is infact much more sucessful for the film. They did attempt to make endings, where they lost the money but got off the cliff safely, and where they went over. But there actually is no knowledge if the bus went over or not.

Clarification:In the movie, The Italian Job, the van containing the crew who were betrayed by Steve (Edward Norton) did plunge over the side of the dam into the water. There John Bridger (Donald Sutherland) dies, while the rest of the team swims ashore with his body.