The one thing I don't like about a rainy day.. the entrance plaza and Main Street brick surfaces are
very slippery when wet! Combine slippery with worn out treads on my
crocs and I nearly face planted several times last March.
Skidded my way into a store where I bought the wooly Mammoth Disney crocs, had toasty dry toes for the rest of the drizzly wet week.
Other changes... if it's pouring or continuing rain, they close up most of the ODV carts. They re open as the rain ends... the CMs with ice cream carts look bored on a rainy winter day.

The waterfall path at DLH closes for safety reasons.
And the ducks inside the park happily march around the walkways, last year a mama duck paraded her fuzzy little ones all around the partners statue. They were eating spilled popcorn under a cart, the disney policeman was carefully following to make sure no one bothered them. Only at
Disneyland!