In mid 2012, Ron Perlman once again endured the 4-hour makeup routine required to transform him into Hellboy, to fulfill the Make-A-Wish request of a six-year-old boy named Zachary who had leukemia. Creature effects house Spectral Motion, who had worked on the two previous Hellboy films, applied Perlman's Hellboy makeup (and later, also made up Zachary as Hellboy as well), so that Zachary could spend the day hanging out with his favorite superhero. Guillermo del Toro was so touched by this event that it inspired him to re-start production on the shelved Hellboy 3. However, after several years without progress because del Toro was working on several other projects, the studio had approached Neil Marshall to helm the next film, and decided that it had to be a reboot to set it apart from del Toro's vision. Del Toro's Hellboy III was subsequently announced to be canceled, and this reboot's development started soon after.

During the battle with the three giants, the zipper on the back of David Harbour's Hellboy muscle suit is briefly exposed when his trench coat flips up.

There is a mid-credits scene featuring the team, and a post-credits scene featuring Baba Yaga.

Featured in Jimmy Kimmel Live!: David Harbour/Bob Pflugfelder/Rodrigo y Gabriela (2019)