Cast the Expert: Joe Cornelius, who had wrestled for twenty years as a character called 'The Dazzler', was cast as Trog because of his athletic ability.
Freddie Francis later called it a terrible film, and said it was the one he regretted he directing.
Joan Crawford immediately disowned the film upon its release.
"If I weren't a Christian scientist and I saw Trog advertised on a marquee across the street, I think I'd contemplate suicide."
Friendship on the Set: Joe Cornelius in 2015 described Joan Crawford as "lovely" and great to work with, giving gifts to all the crew, and sending him Christmas cards every year until her death in 1970.
No Budget: The budget was so limited that actors supplied their own costumes, and filming had to be abruptly stopped due to cuts.
Production Posse: Joan Crawford and Michael Gough had starred in Berserk, produced by Herman Cohen too.
Reality Subtext: Dr. Brockton sadly walking away from the press at the end of the film feels like an even harsher ending when one remembers that this was Joan Crawford's final film role. It isn't hard to interpret the scene as a metaphor for Crawford resigning herself to turning her back on Hollywood.
Star-Derailing Role: Joan Crawford was being steadily reduced to B-movies and bit spots on TV after being fired from Hush... Hush, Sweet Charlotte, a Spiritual Successor to Whatever Happened To Baby Jane which would've reunited her with co-star and rival Bette Davis before their acrimony reached a tipping point. Her difficult behavior and alcoholism didn't do her any favors, either. This film's failure made for an unsuitable swan song for Crawford on the big screen, as her scant appearances afterwards were mostly on TV.
Stunt Casting: John Hamill, who played Cliff, was cast entirely so he could strip to his underwear. He was one of England's top physique models in The '60s.
Urban Legend of Zelda: Joan Crawford allegedly drank Pepsi bottles full of vodka to be able to say the film's dialogue with a straight face. Joe Cornelius disputed this however, saying he never saw her drunk on set.
What Could Have Been: The film was originally going to be titled The Missing Link.
The cabinet's control panel art was designed with the original bone-placement mechanic in mind, featuring the hands the players would control and the colored bones they place.
The Trog's Cave intermissions have a few odd qwirks leftover from the prototypes:
In the proto, the first Trog's Cave sets up Trog's motive for wanting to hunt the dinos, and sure enough they start spawning on the next level afterwards. In the final game, they spawn right from the beginning.
A later Trog's Cave shows Trog imagining destroying the bones barricading off parts of the later islands. This is a leftover from prototypes in which the Trogs could smash placed bones and make it more difficult to trap them, but in the final game they never obtain the ability to destroy bones in any capacity, even the used to dive sections of the levels.
Saved from Development Hell: Originally, "bone placement and guide dinosaurs" gameplay was to be used the release version, but after being unpopular with testers, it was planned to be shelved and never see a wide release. Then, at the hands of one of the testers, it was suggested that the dinosaurs were directly controlled instead of the color-coded hands and the gameplay retooled into something akin to Pac-Man. The idea stuck and the game's ruleset was altered as a result.
What Could Have Been: In the prototype, the player didn't control his/her dino directly, instead, they laid bones in the dino's path to force it to turn. This however proved to be too confusing, so a more conventional control system was implemented where the player assumed direct control over their dino instead and upped the aggression of the Trogs in the process.
