Hi, Alexandria!
My daughter lives in her flip flops. Regardless of where we go, her slip on, yoga mat flip flops are her "go to" shoes! You will find this to be a common shoe-of-choice when visiting the Disneyland Resort.
There is not a restriction on wearing open toed shoes when enjoying attractions at either
Disneyland Park or
Disney California Adventure Park. You may need to slip them off during
Soarin' Around the World where your feet are dangling, but in most other cases your footwear will be safely on your feet!
When choosing your shoes, pick something super comfortable. It is not uncommon to walk several miles in a day, and there is nothing worse than sore feet. If you are planning multiple days in the parks, bring along a second pair of shoes and alternate each day.
My big question is how does Minnie Mouse wear those darling yellow pumps each day? She really is amazing being able to wear heels day in and day out!
Enjoy your visit to the Disneyland Resort!
Cathy