In a few of the later episodes, Leopold the Cat appears to be bare chested. In one of the episodes, two mice are bare chested as well. However, there is no nudity.

Most of the episodes have very mild but cartoonish violence, which mostly involves a cat and two mice doing stuff against each other. A few times, some other animals are involved as well. Nobody dies. However, the level of slapstick violence are basically nothing compared to what you'd see in other stuff like "Tom & Jerry".

In the first episode, Leopold the Cat consumes an amount of aspirin tablets, and becomes strong.

None. This Soviet cartoon series is excellent for everybody.