The Powerpuff Girls Best Rainy Day Adventure Ever / Just Desserts - S2-E10
Continuity mistake: When Marrianne calls Harold to the table, the plant in the middle disappears as they climb on top of it.
Continuity mistake: When the girls first came out of the machine, they were actually just the size of insects, and the professor didn't need a helmet to see them, but when they was during the battle, he had to.

Buttercrush / Fuzzy Logic - S1-E4
Continuity mistake: When Buttercup punches a hole in the wall to see her sisters are being lowered into lava, the hole's initially quite small. In the next shot, the hole is noticeably bigger.
Answer: It depends on where Blossom found the new blanket. For example, if she found the blanket for sale brand new in a store, she would know it wasn't Buttercup's real blanket.
BaconIsMyBFF