The Stranger Things star takes over the title role in the new film, which has already been filmed.
But filming on location in Bulgaria did have its downsides, according to Harbour – including an “unhealthy” relationship with Twitter.
Asked to describe where he was staying, he said: “It’s very Eastern Bloc…
“There’s things they don’t understand – like shopping. You’re in a drug store and people think it’s a cafe, you’re just there to hang out, there’s no shopping. Things like that are a mystery to them still, at this point.”
Appearing on Jimmy Kimmel Live, he said he would spend his free time sitting “at home in [the] hotel and smoke cigarettes, thinking about what’s happened to your life.
“But I got the suit and I got stunts and I’m 40-years-old so I’m beat up to hell, and I’d come home and lie on my horrible Bulgarian couch in my hotel and go on Twitter, so I got very into Twitter at the time. Unhealthily so.”
Recalling one incident that saw him promising to pose for one fan’s senior photos, he continued: “I go through phases but at that point season two [of Stranger Things] had come out and people were tweeting me these ridiculous, hilarious things and I started to engage.
“I took senior photos with a young lady… I said, ‘if you get 25,000 Retweets I’ll take your senior photos, provided I get to wear the school sweatshirt and hold a trombone.”
When Kimmel checked this had all taken place from his couch in Bulgaria, Harbour reaffirmed: “Yeah! These were the mistakes I was making!”
The Hellboy remake has wrapped and is expected to be released on January 11 next year.
Harbour is joined in the case by Ian McShane, Kristina Klebe, Milla Jovovich, Sophie Okenedo and Sasha Lane, among others.
The 2004 film starred Ron Perlman in the top role and made $99.3 million at the box office, generating mostly positive reviews.
Sequel Hellboy II did even better, making $160.4 million at the box office. However plans for a Hellboy III never came through.
Hellboy is out on January 11, 2019.