Hey there, Hi there, Ho there, Dawn!
Welcome to the Disney Parks Moms Panel. Oh Boy! How exciting that you will be celebrating the birthday of the big cheese himself at the Disneyland Resort. Last year I happened to also be vacationing at the Disneyland Resort for Mickey's birthday on November 18th, and I will never forget this iconic celebration.
Though not all details have been released just yet for what in-park activities will be taking place on November 18, 2018, I can let you know how Mickey's birthday was celebrated in the parks last year. First, we were given complimentary "Happy Birthday Mickey" buttons upon entering. These were limited, so I made sure to arrive early. Next there were Disney PhotoPass locations around the parks where you could hold "Happy Birthday Mickey" props to remember this special day. In Disneyland Park there was a birthday cavalcade down Main Street, U.S.A. to honor Mickey Mouse as well. The
Disney Parks Blog actually did confirm that this will be returning for Mickey's 90th birthday! I wouldn't be surprised if we saw some special merchandise for this occasion in the parks as well. Keep an eye on the Disney Parks Blog for more details as your trip approaches.
I hope this helps, and See Ya Real Soon!
-Jennifer