The nudity in this film is limited to immediately after Karik (Aleksei Chertsov, 9) and Valya (Anna Dikul, 7) shrink in size. They fall into the water, and we see their nude back-sides as they fall. Afterward they wear loincloths.
In the first 10 minutes when the boy Ravenfeather (Vaclav Tvaroh, 9) only wears a loose loincloth. It fails to cover anything when he's struggling or carried by someone, front and rear briefly seen a few times.
Martin is trapped on a tree house and makes a rope from his clothes to climb down from a tree. On the way down he gets his underwear caught on a branch. His underwear tears off and comes off him. Martin ends up completely naked save for his socks and shoes and runs off.