During the filming of Terminator Salvation, emotions ran high. Too high, in fact. At one point during the filming of a scene the DP walked on set and ruined a shot. More importantly, he ruined Christian Bale's concentration, which led to one of the ugliest movie star melt-downs in a long, long while to be recorded on set.
TMZ recently posted a Quicktime of the audio of this outburst (the sound guy is going to have a hard time finding work after this), during which Bale orders him to be fired immediately. In fact, that's about the nicest thing he says during this nasty little incident.
Source: Jun Sato, Getty Images