Witchstock - S6-E11
Corrected entry: Paige is sent back to when Grams was her age; this shows that they are family and that they share similar traits. Grams having orange hair is a mistake because Paige's hair is not naturally orange, therefore has nothing to do with genetics.
Witchstock - S6-E11
Corrected entry: When Piper and Phoebe appear in the past, Penny chides them not to "use [their] magic so openly." Immediately thereafter, Penny uses magic to turn some police officer's night sticks into flowers. That was some pretty open use of magic, right there.
Correction: Well, I can't remember Penny's exact wording, but even so, if someone saw Piper and Phoebe materialize out of nowhere they would've been exposed. Penny turning the nightsticks into flowers was much less obvious, because the cops would've had no way of knowing how it happened or who was responsible for doing it.
Correction: It is never said once in this episode, or any other episode that Paige had red (or orange) hair because Grams did. Grams can still have red hair, even if Paige's natural color is not.