In the TV movie The Night Stalker (1972), when a refrigerator containing blood is opened there is blood labeled "Benjamin Richards". A prop left over from this production.
Series star Christopher George, whose character supposedly had a medical/genetic condition that made him immortal, died of a heart attack aged only 52, barely a decade after the series ended.
It's been pointed out that Christopher George died of a heart attack at an early age. This was reportedly due to damage to the organ from a Jeep roll-over accident while he was filming "The Rat Patrol" a few years before this series.
The series was based on the 1962 science fiction novel "The Immortals", by author James E. Gunn.
Gene Derrell's, assistant director for seven episodes of The Immortal claimed the series turned into one big car chase, so much so that when producers realized that stunt man, Hal Needham, looked so much like Christopher George there were days when Chris didn't even have to come to work.