Studio publicity material credited René Cardona as co-director and Jorge Stahl Jr. as Lucien Ballard's camera operator, but it is unknown if they ever worked on this picture and likely that they had been only hired to make sure union requirements were fulfilled.
The Spanish infantry are wearing 17th century motion helmets. Those helmets were out of fashion long before 1769, the year this film takes place.
The real Fr Junipero Serra was beatified (called "blessed") by the Catholic Church some years ago, which is the first step towards sainthood. He is now referred to as Blessed Junipero Serra.
Original literary source: "The Nine Days of Father Serra", novel by Isabelle Gibson Ziegler, Longmans Green & Co, New York, 1951, 242 pages.