You mean Lars? (into Lion)

We've already seen that, against most but not all of physics laws, Lars can reach into his own head if Steven is pulling it.

An easy solution would be that the Lars tree actually retracts if Lars enters the Rose Zone and vice versa.

If that happens… can Steven/Rose store pink zombies in their pink dimension? Do pink zombies require oxygen? Can they reach the fifth dimension if they try to enter the hair/mane while they're already there or it will all explode either because they reached the antiverse or just the good ol' "storing a portable hole inside a bag of holding"?