None.

Because the now-dead mother rat was white like Chichi, it was easy for her to get spotted by owls and weasels. It may imply the fact she could have been attacked by either of these animals, but this is never mentioned directly.

A brief scene shows a weasel trying to attack three rats. One of the rats attacks the weasel and bites it's nose.

Three rats are chased by lots of other rats for a long time.

A man kicks away a rat, causing it to crash into a rock wall.

Two sparrows attack several rats, who they believe had killed their baby sparrow. The rats had actually saved the baby sparrow from an ugly accident at a river.

Chichi is almost hit by a motorbike.

None.

In one scene, a cigarette is thrown down into a sewer, right in front of three rats.

There are times in which two young rats and their father get into perilous situations, like being chased by lots of other rats, and caught by a waterflood inside a sewer.