After Dr. Doofenshmirtz hangs up the phone, the phone and the package he's holding both disappear.
The background behind Major Monogram on the screen doesn't match the background behind him at the party.
When the boys ask Isabella if she is sad that Santa put Danville on the naughty list, she says that she celebrates Hanukkah. However, earlier when Phineas asked everyone if they wrote letters to Santa asking him for things, Isabella said that she did; and when he asked if they wrote Thank You notes for the presents they received from Santa, she said that she didn't. Why would she write letters to Santa and receive presents from him if she celebrates Hanukkah?