Continuity mistake: When the two children visit the Ghostbusters the little girl is wearing a pink pajama top and pink bottoms. In the next scene the pajama bottoms change color and are now orange.
The End of Flutter Valley (3) - S1-E3
Continuity mistake: When Reeka is conjuring the fake rainbow to distract the Flutter Ponies, the grey pot on her head is blue for a while.
Yomigaere! Eiyuu Densetsu - S1-E1
Continuity mistake: At night, Seiya is startled by Marin's voice and looks at her. There's a table with wine and fruit to his right. A few seconds later, in another shot of the room, the table moved to the left. (00:12:40)