Continuity mistake: When Phoebe and Max are tied together, the whip starts to cause sparks to fly in the the air. Then, a lightning bolt appears and Electress (really Barb) pops up and says "shocked to see me?" and the whip isn't sparking anymore.
Suggested correction: Her presence stops the whip from sparking as it was her weapon.
But wouldn't the fact that Max and Phoebe are touching the whip also keep it from sparking? True, it's not their weapon, but they are "supes," so their powers should have prevented it.
Other mistake: Even though Max nor Phoebe control the whip, just the fact they are "supes" should have allowed them to control it.
Revealing mistake: When the whip is sparking, no black marks are left on the floor.