Rendel had 22 production masks during the filming and 18 got broken. Masks are handmade.
Majority of scenes were shot in Renforsin Rannan yritysalue area in Kajaani, Finland. The area used to host a paper mill, one of the largest in Europe (a total of three paper machines). The mill was closed in 2008 and nowadays the machinery has been removed and the area hosts around 35 businesses. The biggest machinery halls are more than 8 000 m2 in size (250 meters long and 20 meters high). Rendel was shot in a total of around 30 different locations in Renforsin Ranta area.
The first Finnish superhero movie to be made.
Rendel was almost completely shot on location. There were a total of 101 locations. Only one shooting day was set in a green screen studio. A total of 23 locations had no props at all, just an empty space, before the set design team started their work.
Majority of the film was shot after sunset. During the shoot the sun set around 6 PM Finnish time.