Although Richard Burton and Stanley Baker had been close friends since they were teenagers, this was the only time they acted together in a movie. Burton later recorded the narration for Baker's movie Zulu (1964).
Richard Burton was 29 at the time of filming, but many critics felt he already looked too old to play Alexander. He was supposed to be a teenager for the first hour.
Charlton Heston turned down the title role, saying, "Alexander is the easiest kind of picture to make badly."