Plot hole: During the Green Candle, in series 1, we are told that the only reason Tommy's Green Ranger powers could be drained is because he touched a special wax. However, Kim, Billy, Zack, and Trini did not touch the special wax, therefore the candles shouldn't have stolen their powers. When they were captured, they were transported straight to a prison cell as Goldar lit the candles, therefore the Rangers couldn't have touched the candles when captured.
Suggested correction: Different candles. A different idea. Just because they did things one way, one day doesn't mean they absolutely have to follow those rules the second time and apply to different people. They could have changed the plan.