Waterworld | Image: Universal Pictures
It's often a bad sign for a movie if during production it runs excessively over budget. It's not as much of a problem if the movie ends up being hugely successful, as at least one of the movies on this linked list was. Yet if the film is a flop, being over budget during production compounds the disaster.
A good example of that compounded catastrophe is the Kevin Costner tanker Waterworld. This universally panned dud was a production nightmare from start to finish. The set was an expensive enclosure built on the Pacific Ocean, a move which necessitated the cast and crew commute to work via jetski.
Perhaps sensing impending watery doom, Costner was picky and tempermental. For example, he insisted that the original score written for the film by Mark Isham be thrown out due to being too "ethnic and bleak." Joss Whedon was rushed to the set in hopes of saving the script via rewrites; it only strained the budget further. At the end, the production was $75 million over budget.
Read about twelve more films that went far over their production budgets here.