Continuity mistake: The Power Chamber drastically changes between the previous series and this one (for example, the old Rangers' costumes and weapons aren't shown), yet no explanation is given.
Continuity mistake: Only a minor mistake - when Japanese footage is used, the Rangers, Elgar, Rygog, and Porto look slightly different - for example, Elgar & co. look more menacing and detailed (compared to their American counterparts), whereas the Rangers costumes are made of a different material.
Shift Into Turbo: Part I - S1-E1
Plot hole: Divatox and co. live in a submarine in Angel Grove lake. In "Hogday Afternoon", Angel Grove lake was drained to about 30ft at the deepest. The lake would have to be several hundred feet deep for a large submarine to hide there.
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.
Plot hole: Everything in the Youth Center is in hieroglyphics because of the magic staff. Look carefully at the arcade machines in the background - the writing is still in English.
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.
Continuity mistake: When Carlos is passed the ball during the football game, he has 2 defenders either side of him. In the next shot, Carlos hasn't moved, yet he now has no-one around him.
Honey, I Shrunk the Rangers: Part 1 - S1-E16
Deliberate mistake: Monkey Bulk & Skull are driving Lt. Stone's car. From inside shots of the car, Monkey Bulk's head doesn't go above the headrest. From outside shots, we can see the guy who was driving the car - his head is way above the headrest, and he's wearing a frizzy fur costume (Monkey Bulk & Skull's fur is very fine).
Honey, I Shrunk the Rangers: Part 1 - S1-E16
Continuity mistake: The sign outside the Youth Centre changes in this episode, yet is back to normal in the next episode.
Passing the Torch: Part 2 - S1-E19
Plot hole: In the first episode of series 4, we are told that the Power Chamber was directly below the Command Centre. In Hogday Afternoon, part 2, at the end of series 3, the Command Centre was completely destroyed - so how could the remains of the Command Centre be next door to the Power Chamber?
Continuity mistake: One at a time, the Rangers jump down a tunnel into the Phantom Ranger's service tunnels. After TJ has jumped down, watch Carlos - his position changes between frames, and the camera is on him the whole time. First he is facing the hole, next he has his back turned - yet we do not see the movement.
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.
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.
Continuity mistake: Bulk, Skull, Ashley, and Cassie are playing tennis, and they leave their rackets and balls behind them, at the back of the tennis court. When the Piranatrons attack, the rackets and balls are gone.
Beware the Third Wish - S1-E31
Continuity mistake: The Wicked Wisher throws giant exploding coins onto the field TJ is on, as TJ runs towards the WW. The giant coins remain on the field after they explode, yet when TJ reaches the top of the field, there is no sign of the coins, or their remains.
Chase Into Space: Part 1 - S1-E44
Continuity mistake: The space shuttle at Nasada - first it is below ground (as shown by the little amounts of light), then it is in the open (we see the Rangers get inside the shuttle, and it is a sunny day), and then we see the shuttle be raised up from the underground.
Chase Into Space: Part 1 - S1-E44
Continuity mistake: The Rangers try to use the Rescue Megazord's Artillery Power to defeat Divatox's monster. After it fails, the monster blasts energy at the Rescue Megazord - at which point its shoulder-mounted Artillery cannons disappear. They reappear again in the next shot.
Answer: The Rangers are human. Blue Centurion is a robot/cyborg.