Other mistake: If you look closely at the army of Rangers in the opening credits, you can see four versions of Tommy Oliver: Green Ranger, White Ranger, Zeo Ranger Red, Black Dino Ranger. Even though he had a single clone made, he can't be four variations at the same time.
Continuity mistake: When the mother and father are frozen in the park, the dad is holding a napkin up near his chin; but in the subsequent shots his hand is on his lap.
Last Laugh - S1-E12
Continuity mistake: When Gia is pulled into the urn she is in her civilian clothes, but when the urn is destroyed, she comes out in her ranger uniform.
Deliberate mistake: Many of the Rangers in the Legendary Battle could not be there since they were portrayed by the same person. All 3 Rockys, all 3 Adams, and both Jasons and Kimberlys were all present.
Other mistake: Tommy appears as the Green Ranger; this is not possible since his Green powers were lost forever in MMPR season 2 which led him to becoming the White Ranger.
Continuity mistake: When they are showing every past Ranger rescuing someone. In the part with the rocking car, Tommy comes down on the car, he reaches for the boy with his left hand. Show above view, he's holding his right hand. Switches to the front view, left hand again.
Visible crew/equipment: When the Rangers are talking to Tommy and the other Rangers, the pink ranger helmet is reflecting the mic above.
Continuity mistake: Troy's morpher was destroyed yet when he is being held for ransom, he is in his ranger costume.
Other mistake: The legend rangers have cameos where their Ranger helmets reveal which team they fought with. Tommy has the White Ranger helmet appear and even uses Saba (his White Ranger weapon) to rescue a child from a car but he actually fights as the Green ranger in the war.
Visible crew/equipment: You can see cameras, crew and what appears to be a bonfire reflected in Emma's visor when she is dressed as the White Wild Force ranger. (00:15:00)
Character mistake: Troy calls for the "Twistornado" but his card reads "Windrive"; the cards have always read exactly what the rangers called for.