Deleted Scene: Actors at Conventions have commented on various scenes filmed that didn't make it into the movie, such as the Rangers doing some preliminary training between being given the ninja robes by Dulcea and traversing into the forest. In particular, Tommy's was apparently seen practicing some superhuman kicks similar to the corkscrew kick he used to finish off the last gargoyle.
The first fight scene in the construction site involved the Rangers fighting mutant, humanoid rats. However, it was universally agreed upon that the rats looked absolutely horrible, and they were replaced with the Oozemen. The rats later showed up in the TV series, in Season 2's "Return of the Green Ranger."
The Tengus were used in the third season as the Tengas.
Much later, one of the stone gargoyle-guardians the Ninjetti Rangers fight appeared in the background of an episode of Power Rangers S.P.D..
The Other Darrin: Rita is portrayed by a different actress, though, thanks to her voice already being redubbed, she sounds just the same as she does on the show.
The Other Marty: Mariska Hargitay (Yes, that one) was cast as Dulcea, after the original actress had to back out to remove a cyst, then she returned when filming ran longer than expected.
What Could Have Been: The producers originally intended for the Rangers' masks to not have their visors and mouth pieces, feeling that it removed any sense of personality. They realized that their changes were counter-intuitive to the point of wearing a helmet because they were supposed to be an elite, faceless fighting force. They went overbudget and over schedule to refilm the necessary scenes. This actually resulted in the second season of the show overlapping with the film production (they were supposed to finish filming it when they returned home to America), the last few episodes were filmed in Australia.
This is actually for the best as pictures of the visor and mouth piece-less helmets have shown up and they looking incredibly awkward to say the least.
Austin St. John (Jason), Walter Jones (Zack), and Thuy Trang (Trini) were originally slated to appear in the film, but due to their contract dispute halfway through Season 2, they were dropped.
After Ivan blew up his Tengu Warriors for failing, he created a colorful-feathered "Queen Tengu" out of their feathers.
Catherine Sutherland (Katherine Hillard, the second Pink Ranger) auditioned to play Dulcea. Evidently they liked her enough to bring her to America for a role. Sutherland has lived in America since.
Mariska Hargitay was cast to play Dulcea after the original actress, Gabrielle Fitzpatrick, had to back out due to a scheduled surgery. The producers didn't feel that Hargitay was working out and was replaced with Fitzpatrick after she recovered. Due to budget issues, she wasn't able to refilm an extended sequence where Dulcea trained the Rangers in their ninja outfits at her home. As such in the movie the Rangers seem to just sit and stare at the monument for a time before deciding to go.
Ooze originally created a team of rat-men to battle the Rangers at the construction yard. The director and producers felt they looked horrible and very low-budget (their goal was to create a high-budget looking movie) and such convinced 20th Century Fox to replace them with the more creepy looking Ooze-men. The rat-men costumes were later used in the "Return of the Green Ranger" three-parter on the TV series.