I can remember seeing a movie years ago, but can't for the life of me remember what it was called. It was about a group of adults who realise the have to try to get their childhood friend out of a mirror having accidentally trapped her in their during a game when they were kids. Anyone know what I'm talking about here? I'm starting to get slightly frustrated :(

Sounds a bit like...
The Watcher in the Woods - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/The_Watcher_in_the_Woods)

Sounds a bit like...
The Watcher in the Woods - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/The_Watcher_in_the_Woods)

Yeah! That is it, thanks very much :)