It is the usual - but, if you wait at the castle end near the character points you get a chance to be there at the start of the "scrum".
They do have a "minder" for each character - they all have to leave together to get back on the train- so if you see any of them heading back to the train, be aware that they will all leave sharply. Also, when we were there, Buzz and Eeyore couldn't sign autographs - my girls took all their time trying to get to Buzz and were disappointed - even though we got a lovely photo of them with him!!
Tessa