If I Had the Wings of a Bugaloo - S1-E5
Other mistake: After Courage and Joy are free from the glue traps, there is still glue on their feet, yet they walk without any trouble.
If I Had the Wings of a Bugaloo - S1-E5
Other mistake: Joy's feet are stuck in Benita's glue trap, but she steps backwards twice before Harmony and Courage pull her out.
Firefly, Light My Fire - S1-E1
Continuity mistake: Joy exits her house twice: once after the curtains pull back, then a second time after Harmony says his line.
The Great Voice Robbery - S1-E3
Audio problem: Several times throughout the episode while the characters are speaking in other people's voices the spoken words don't match the lip movements.
Firefly, Light My Fire - S1-E1
Revealing mistake: Courage winces and reacts before the stereo-zapper is fired.
Firefly, Light My Fire - S1-E1
Continuity mistake: When the boys are tied up, they begin with their feet tied but in the next shot, IQ and Courage have their feet separated.