When Paige orbs Maya into jail and Piper out, they are both wearing orange jumpsuits, but it is unclear where Maya got her jumpsuit from. If she was simply being switched with Piper, then she would have orbed in wearing her normal clothes.
The height from which Maya falls off the balcony means that she would have died or been severely injured upon landing, even with the mattress placed underneath her. Piper's powers do not slow velocity after she unfreezes people, so Maya's safe landing cannot be explained that way.
When Piper unfreezes *just* the D.A.'s head after he has fallen from the skyscraper, his head would have continued plummeting at the velocity it was going even though the body did not, causing it to rip from his body and slam into the ground.
When the witches are "haunting" D.A. Nance, Billie makes him think his hands are old and wrinkly. When he holds his hands up to show what it is he sees you can briefly see the edges of the actors actual hands below the suit cuffs on the fake, old hands.
When Maya meets Piper for the first time, Piper still looks identical to Maya thanks to the 'new identity' spell. Maya doesn't know about the spell, yet she shows no sign of being surprised or shocked at meeting her doppelgänger.