Trivia: When Prince Nuada reassembles the three pieces of the crown, the screws in the crown can be momentarily seen before a shine passes over it.
Trivia: Part of the film's publicity campaign included various parody shorts where Hellboy would cameo on television shows such as American Gladiator, Ghost Hunters and Inside the Actor's Studio.
Trivia: Guillermo Del Toro based the Bethmoora royalty on early European monarchy, when white skin was a symbol of purity and signified that they lived in luxury. Del Toro was also intrigued when he read that much of this early European monarchy was haemophiliac, and thus had Prince Nuada and Princess Nuala prone to easy bleeding.
Trivia: During the auction scene, there's a man with a dog on his lap. This man is Santiago Segura, a Spanish actor. He was the underground train driver in the first film (the one who knocked HB down the train with a fire extinguisher).
Trivia: A third film was rumored for many years, though director Guillermo del Toro confirmed that it was unlikely due to the projected high budget the story would required. After one final attempt to get the film made in early 2017, he officially announced the project was dead. Though shortly thereafter, a reboot being co-written by series creator Mike Mignola was announced. Del Toro and series star Ron Perlman have both given their blessing to the new film.
Trivia: When Abe and Manning are walking down the chaotic hallway of the BPRD near the beginning of the film, the creature seen through a dooway (like a large stalk with tentacles) and the subsequent goblin-like creature being carried by one of the agents both reappear as background creatures in the Troll Market sequence.
