There is a princess or rich girl who wishes that her baby brother would leave and go to hell or go to another land. She regrets this, from what I remember, and goes off to find him. She ends up in a different world with talking spiders.
One scene I remember is the baby being dropped in a tunnel and thousands of hands come out and grab at it.
I was in kindergarten when I saw it and have wanted to watch it again but can't find the movie and don't know the name.

It vaguely sounds like,.

Labyrinth

A teenage girl has to baby-sit her cranky baby brother for an evening. He's crying and she's at her wits end. She started to tell a story about a little boy taken away by goblins. She wishes that the goblin king would take her brother away. Someone was listening, because at that moment,the lights went out, and when they came on again her baby brother was gone.
The goblin king appears in the nursery and tells the young woman that if she wants her brother back she'll have to go to his goblin kingdom and make it through the dangerous maze surrounding his castle. If she fails to do it in time her baby brother will become a goblin.

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you are amazing!! This is exactly the movie I was thinking of =D