Revealing mistake: The footage of Monkey Bulk doing flips is just one backflip forwarded and reversed several times - as evident by the movements of the people behind them.
The Fall of the Phantom - S1-E28
Revealing mistake: When Elgar is sprinkling the gold dust on Cassie, you can see her start to smile and withhold a laugh. She's supposed to be asleep.
Answer: The Rangers are human. Blue Centurion is a robot/cyborg.