In the opening scene with "That's What I Love About Christmas", two ponies (a purple and orange one) are holding candy canes in their mouths. Albeit in the next shot where they're looking at a Christmas store when the song brings up Santa, the candy canes have vanished.
In the end of the movie where the ponies are celebrating Christmas, the sky scenery goes from twilight to dusk in two shots.
Rainbow Dash's necklace disappears and reappears in several scenes, when all of Ponyville is given a first look at the Here Comes Christmas Candy Cane.
Within the scene where Minty interrogates with Pinkie, her facial expression in one shot is worried albeit in a two-shot between Pinkie and Minty, she is smiling.
Minty's cutie mark and her hair changes frequently throughout the film.
When Pinkie puts a star on the tree in the beginning of the film, she has a finger; actual hooves don't have any digits on them.
When Pinkie tries to comfort Minty about the candy cane accident, her eyes go from worried to neutral.
When Sweetberry samples of one of the ingredients for the next Christmas Candy Cane by Triple Treat, her mane has a piece flicker from purple to teal and back again as she moves.