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.
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.
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