Zulu at 50

The Telegraph:

This was Michael Caine's first major film role and, although he eventually put in an exceptional performance as Lieutenant Gonville Bromhead, he was crippled by nerves and beaten to the role he initially auditioned for, that of Private Henry Hook, by James Booth. Interestingly, Caine was also unable to ride a horse so a member of the filming crew took his place in the scene where he crosses the stream on horseback at the beginning of the film. This explains why the camera pans down on to the horse.