Because Robert Powell looked so much like Jesus in pictures, every time he exited his dressing room in costume, the foul language the crew was using would suddenly stop.
While shooting in Tunisia, the set had a surprise visit by R2-D2. George Lucas was shooting Star Wars: Episode IV - A New Hope (1977) at the same time and, according to actress Koo Stark: "Operated by remote control, R2-D2 had to trundle off camera and disappear behind a sand dune. But the remote control failed to stop the robot and he wandered onto the set of Jesus of Nazareth."
Robert Powell has stated he dislikes how some Christian churches use pictures of him in his Jesus costume as objects of worship.
The eye make-up for Robert Powell consisted of a thin line of dark blue eyeliner on the upper lid of the eye, and a thin line of white eyeliner on the lower lid. This had the effect of highlighting the piercing blue of his eyes, thus giving him a penetrating stare, when combined with very little blinking, made the character appear surreal and supernatural.
In a 2019 interview, Robert Powell admitted that, while he wasn't personally religious, he did have, what could be described as a religious experience when shooting the Sermon on the Mount scenes in front of hundreds of rapt and tearful extras. Many of the crew were also deeply affected and highly emotional afterwards and praised Powell for his intense performance.