Charmed (1998)

Once Upon a Time - S3-E3

Continuity mistake: When Kate was drawing the trolls in one shot she had a peach coloured crayon, and in the next shot she had a purple crayon.

Once Upon a Time - S3-E3

Continuity mistake: When the trolls attacked Piper outside P³, her bag got flung into the shadows, but in the next shot, her bag was right next to her, and in the light.

Once Upon a Time - S3-E3

Continuity mistake: The only way any of the charmed ones can see the fairies is with the fairy dust, but in several other later seasons and episodes when the charmed ones need the magical community's help they can see the fairies without any help from fairy dust or a spell.