Talked w/ a cast member and told me the follow hidden things:
Hidden Mickey: In Harry Hausen's - The silhouetts of rioting guests. Mickey full outline.
Hidden Boo (pictured below/ close up) - on the landing bar of Child Detection Agency helicopter. (2nd helicopter, towards end of the ride.)
Hidden Superstar Limo figurine - In the open yellow locker on the right hand side in the locker room.
Hidden Hollywood Tower Hotel towel (pictured below) - After the yellow lockers in the locker room, turn around to face backwards as you leave the locker room. On the right hand side you will see two towels. One is a TOT towel.
Hidden Haunted Mansion wall paper - When Boo hits Randal, he changes colors/patterns. The 3rd in the sequence is HM wallpaper.
Hidden Mickey - on the final Sully, his left leg.