Help! Film with a mirror, a witch and I think soldiers on a giant staircase dancing

Hi there,

This is my first post here. I hope this post is appropriate! Tell me off if not!

I'm looking for a classic film which I remember snippets of from childhood. It's the kind of thing that has just endlessly bugged me because I've never been able to find out what film it was. It is always possible that my memory has conflated two different films into one!

The film I'm looking for was a 50/60's(??) musical in the style of Babes in Toyland or Seven Brides for Seven Brothers. That kind of thing. So big american sound stages and technicolor etc.

The bits I can remember are:

1. One of the characters (the woman I think), if she looks in a mirror a witch appears.
2. a chase through a hall of mirrors at a funfair
3. (This is where I might be mixing different films together) a huge dance/chase scene with the characters running through a vast white stage/room with long steps down which they get chased by soldiers - possibly toy soldiers. The room is huge and expansive - reminds me of the classic umpa lumpa dance scenes in the classic charlie and the chocolate factory - in my head at least.

Things I know:
It's NOT Babes in Toyland or The Witches Mirror.

If anyone can help put me out of my misery I would be delighted!! I've been trying to work this out for about 20 years or more! Thank you!