None.

Planet Krypton explodes, leaving Superman the sole survivor.

By using a deadly ray machine, a villain threatens to destroy everybody who laughed at him.

A villain kidnaps Lois Lane, but most of it happens through silhouette.

A famous bridge is hit by a ray and explodes.

A huge building is shot with a laser, and is about to get demolished when Superman comes to the rescue.

Prior to the falling building, a man is briefly seen getting hit by an object, but if he survives or not remains unknown.

In a letter, it says "Beware - you fools!" along with a serious threat.

In one scene, little smoke can be seen during a conversation scene, making it implied a character must have smoked something.

Using his deadly machine, a villain threatens to destroy everybody who laughed at him, and eventually cause the "greatest destruction the world has ever known".

Compared to what's seen in most modern Superman animated films, such as "Superman: Unbound" and "Superman/Doomsday", the level of intensity shown here is basically nothing. This short cartoon can be watched by children.