Continuity mistake: In the first episode where the Emergency Wizards appear, you can see that the Goblin has 4 legs. Every episode after that with the Emergency Wizards in it, the Goblin has 2 legs.
Suggested correction: In the episode "Harper Knows" he is on stage with 4 legs as a distraction.
Continuity mistake: In the mummy episode, Juliet states that sunlight kills her. However, in the episode before that (Three Monsters), she is shown walking into the sub shop with a calzone box during the day.
Suggested correction: In "Wizards vs. Vampires: Tasty Bites" Harper talks to Juliet about how she's outside during the day without an umbrella because it's cloudy. Meaning that it's only direct sunlight that will harm Juliet.
Rock Around the Clock - S4-E25
Continuity mistake: In episode 25 of season 4, Harper mentions still being in school and even goes to school during the 50's episode to keep her "perfect attendance." But a few episodes earlier, her and Alex both graduate, and even have an apartment. The episodes seem out of order.
Suggested correction: Yes, episode 25 "Rock Around the Clock" was the 14th episode produced (production code 414) and occurred before they graduated the 17th episode "Wizards vs. Asteroid" (production code 418). This isn't a TV mistake since it was produced in order.