Absolutely nothing, unless you count with a scene in which the Snow Queen gives a young boy a kiss on his head as a reward.

Very mild cartoon violence for a film rated U in the UK. No gore.

A troll falls down the ladder he stood upon, causing is hammer to fall on the foot of another troll. This scene is made humorous.

The Snow Queen threatens several trolls to be feed to bats.

A fragment of a now broken mirror falls into the left eye and the chest of a young boy, causing him to become evil.

A boy attempts to stomp on a sparrow.

The Snow Queen grabs a bat, and appears to be threatening toward it.

The Snow Queen cuts off the rope of a sleigh, causing a young girl to fall off and accidentally land on a sparrow. The girl is okay, but the sparrow is kinda hurt but okay.

A cat attempts to attack and eat a sparrow several times.

A sparrow makes a brief reference about "cutting people's heads".

Several trolls make discuss about if the Snow Queen has to kill a young boy in order to gain the last two pieces of her magic mirror.

Several rats kidnap a girl and rob her stuff.

A rat points at a pot of boiling water and mentions a girl who "got to go", making it implied he want's to have the girl put into the pot.

A flying reindeer mentions about having crashed into a tree, and did wake up only to find out he was tied up in rope.

The Snow Queen freezes a troll into ice for a while. Afterward, the troll appears to be fine.

Just a few brief but mild insults which you can expect in any G-rated animations (or any U-rated animations from the UK in this case)

The Snow Queen calls several trolls "fools".

A boy utters "stupid kids".

A witch can briefly be heard saying "naughty" toward her cat.

None, unless you count with several rats drinking some dirty stuff, similar to how people drink alcohol during party.

Some of the villains want to kill Ellie for their reasons, and may frighten some very young children; A seemingly innocent old woman turns out to be a witch who wants to take the heart of the girl, and a rat thief wants the girl to be put into a pot of boiling water. These scenes are, however, very mild.

Some very young children may find the Snow Queen to be scary in several moments.