David Harbour gave "Hellboy" producers one **** of a scare ... he almost didn't fit into his demon superhero bodysuit because he was too jacked!!!
Harbour's trainer, Don Saladino, tells TMZ ... Harbour's 10-week workout regimen transformed him so much it set off a production panic. We're told producers were actually upset over the weight loss and body reshaping.
Vid - Celeb - Trainer - Case - Harbour
Check out the vid ... the celeb trainer says it wasn't the case. He concedes, yes, Harbour's body drastically transformed...