A burst vessel became a camera problem
Holding his breath underwater put Hamill under physical strain, and a small blood vessel broke, leaving visible redness on his face. That mark could not simply be reset between takes: unlike a costume or prop, an injury may remain visible while a scene is being filmed.
For a movie, that creates a continuity problem. If the redness appears in one shot but disappears in the next, viewers may notice the mismatch and be pulled out of the action.
Blocking around the change
Lucas’s practical fix was to film the remaining action from the side that concealed the affected area. The camera angle turned an accidental change in Hamill’s appearance into something the audience would not see. Rather than interrupting the scene to work around the mark in other ways, the production could keep filming while preserving a consistent image.
It is a small example of how movie scenes are shaped by what happens on set: sometimes the solution is not to change the performance, but to change where the camera looks.
