The rocket ship that Ella uses when chasing the sheep down the hallway is the rocket Wallace built in A Grand Day Out.
Bitzer flies through the air with a snowman. This is a reference to "The Snowman" (1983).
The chase scene in the house at the end is a reference to home alone (original movie).
At about 8:15 the sheep, who have formed into a snowman, advance when you look away, like Dr.Who's weeping angels.