Board Thread:Game Discussion/@comment-31133384-20170124050830/@comment-29191942-20170124210425

They brought back The Incredibles characters (the first event) for a limited time as rewards in mini events and a Legendary Chest, so they may bring the Frozen and Nightmare Before Christmas characters.

They may do it in between updates, but there's another event for Mulan starting on Thursday so I wouldn't expect any previous even characters until at least mid-February.

Also, you need to have cleaned California Screamin' from the curse before you can participate in any event (mini (such as Striking Gold) or full (such as Frozen))