It is implied that the jungle child is naked, yet in at least one shot from the scene of him running away from Steve and his companion, he has on pants or shorts. *This was a TV show in the 70s-nudity could not be shown on network television. This isn't really a goof, but something that the show would have had no choice about.*
Steve and his Japanese friend are supposedly looking for the wolf boy in a deep and wild forest, yet shortly after they start out looking, there is a shot which clearly shows a developed park-like area in the distance, complete with mowed grass and brown-wood benches.
Although set in japan, the jeep they drive into the jungle is LHD. japan have always driven on the left, like the UK.
During his fight with the mercs, Steve delivers a punch with his left (non-bionic) arm, yet the classic bionic sounds are still heard as he swings.