Phoebe bumps into Adam and spills her coffee down the front of her blouse. The stain, however, does not appear until after she has entered her office.
In the beginning of the season 5 episode "Happily Ever After", We see the evil witch killing the keeper of the fairy tails. As she is killing him you see his blood dripping down her hand. However after he is dead, there is no blood on her hand.
Piper puts on the red hood before entering the portal, but it can still be seen under the storybook as she enters.
When Phoebe puts on Cinderella's glass slippers they have suddenly gone from being totally see-through to having cushioned insoles, and you can clearly see the large square black label of the designer.
The ruby shoes from the wizard of Oz that the keepers apprentice gives Piper have button o bow in the front. Piper arrives at the manor the shoes have straps with no button o bow in the front.
In the season 5 episode "Happily Ever After", the characters are embroiled in a storyline involving numerous elements from the "original" fairytales. One of these involves the ruby slippers from L. Frank Baum's book "The Wizard of Oz". But the original slippers were silver - MGM changed the slippers to ruby for The Wizard of Oz (1939) because it looked better in Technicolor.