Some depictions of the process of the reproductive system in animals, though it is done in an age-appropriate way.

In the episode "Get Planted," while exploring a plant cell, the characters see a white, sticky, sweet, liquid coming from the mitochondria and question what it is. Ms. Frizzle then explains that the substance is sugar.

In some episodes they talk about body parts, like your digestive system and muscles, it appears very much like your own body in real life, pretty disgusting for some viewers.

None.

Sometimes, Ms. Frizzle can get herself, Liz, and the kids in dangerous situtations.

Repeated screaming and shouting throughout

The main characters in perilous situations might scare and intense for younger viewers and children.

For preschoolers/kids and up.

Some episodes are slightly disgusting, particularly the anatomy episodes.

Arnold in one episode has a tantrum with the teacher, and takes off his helmet to prove her something, which results in his head getting freezed. This may be unsettling for some viewers.