When Kimberly (Pink Ranger) first exits the water in the mine/quarry her hair is dry.
When the car gets hit by the train, its rear axle gets torn off, but when the car comes to a rest, the rear wheels are still attached.
When Rita goes to the jewellery store she tells the assistant to hand over her necklace. The assistant starts to take it off but in the next shot it is no longer round her neck & Rita is already holding it.
When Billy calls to his friends from the water, Trini (Becky G) is seen laughing and turning around. The angle changes and she's seen standing facing forward with a flat face, while the next angle change has her laughing and turned around again.
When we first see the morphed rangers from the back walking towards the cliff edge to see the gold monster marching towards the city, their helmets from the back can be seen having two pieces, but when the camera shows them from the side with their faces visible, the helmets are one piece.
The end credits of the "making of" documentary on the home video release include a credit for "Abby Road Studios." The first word should be spelled "Abbey."
When running from the Zord in the Black Ranger's original attempt to control it, Alpha 5 pauses mid run (this can also be seen in the trailer) in what seems like a CGI error.
When the teens are swimming through the subterranean lake, while they are nominally swimming down/sideways towards the cave with the ship, the bubbles they're exhaling move "forward" from their face, revealing that they're really facing up, and the effect is being accomplished by altering the camera orientation.
At the beginning of the film, the caption reads 'PLANET EARTH: CENOZOIC ERA', and what appear to be pterosaurs can be seen flying in the background. The Cenozoic is the current geological era, and pterosaurs went extinct in the Mesozoic.
During the fight with the dinosaur skeleton, you can see an SFX member for at least a full second.