Rex Harrison did not get along with Charlton Heston at all during filming. Twelve years later, while filming Crossed Swords, he avoided him completely.

Charlton Heston put a steel rod in his nose to make it resemble Michelangelo's broken one, but Rex Harrison steadfastly refused to grow a beard, even though the real-life Julius II had one.

Laurence Olivier was the first choice for Pope Julius but was unavailable.

Average Shot Length = ~7.5 seconds. Median Shot Length = ~6.8 seconds.

Cardinal Giovanni de Medici succeeded to the papacy after the death of Julius II in 1513, becoming Pope Leo X.

Heston was asked in an interview, which of all the characters he'd portrayed would he like to have as a dinner guest. He said Michaelangelo, but acknowledged that, as the painter did in the film, Michaelangelo would certainly not show up.

In the film, the quarries that Michelangelo (Charlton Heston) sourced for the marble for his sculptures were the actual quarries attended by the real Michelangelo at Carrara, Massa-Carrara, Tuscany, Italy.

One of Michaelangelo's sculptures was of the Biblical figure Moses. Charlton Heston's resemblance to that sculpture earned him the role of Moses as well.

The film lost $8 million worldwide.

The material used as the wet plaster that drips into the mouth of Michelangelo (Charlton Heston) was chocolate pudding.

The movie was originally supposed to have been filmed in 1961, starring Burt Lancaster, but production was delayed for three years.

The Sistine Chapel could not be used for filming the painting of its ceiling so it was recreated on a sound stage at Cinecittà Studios, Rome, Italy.