Shirley MacLaine did not get along during the shoot with director Don Siegel, with whom she openly fought.

While in Austria filming Where Eagles Dare (1968), Clint Eastwood was approached with the sсript by Elizabeth Taylor,
Richard Burton's wife at the time, with the notion of starring together in the film. However, Universal Pictures was unwilling to pay Taylor's high salary.

Shirley MacLaine wrote that since this was filmed in Mexico, it took substantial time to send the film to California for processing and return it for dailies.
When MacLaine finally saw the dailies, she was appalled at how overstated her false eyelashes looked, as she was playing a hooker posing as a nun.
She regretted that she could not remove them for the rest of the filming because the footage would not match.