There is a fear that Harrison Ford will walk and not make a fourth Indiana Jones movie as he has been told that he cannot use a real whip. Indiana Jones is most famous for the use of his whip to help him get out of situation, but he has been told by the studio that it is against new health and safety laws for him to use a real one; instead a computer generated has to be added in later.
Ford has said that this rule is ridiculous, and that he will pull out of the new movie unless he gets his whip back.
Source: inentertainment.co.uk