Bicycle Built for the Blues - S1-E8
Other mistake: Monkey Skull turns on the CD player. As we see him put down the CD lid, look closely - there is no CD in there.
Clash of the Megazords - S1-E29
Other mistake: When TJ goes to get the Phantom Ranger's ruby, he is standing on top of the battery pack on the Turbo Megazord. There are no other places for him to stand. After he destroys and knocks off the battery pack, in the next shot he is still standing in the same place, but there is nothing for him to stand on.
Answer: Scheduling problems with Hilary Shepard Turner meant that she was unable to reprise her role as Divatox from "Turbo: A Power Rangers Movie". Carol Hoyt was brought in as a replacement until the major cast change mid-season, when Hilary returned. Carol still played Dimitria, the Rangers' mentor.