Power Rangers also had a female Red Ranger before Super Sentai: SPD's A-Squad leader Charlie, to Shiba Kaoru, the female ShinkenRed, a 4-year difference. And both characters aren't really good news for the Rangers.
Dawson Casting: Quite frequently. The first season had characters in high school played by actors in their early-to-mid-twenties, some of whom did a better job than others. The trope page compares Austin and AJJ to show how men are less convincing at this than women, especially since Austin was a teenager when he started playing Jason (although to be exact Austin was actually in his late teens, therefore he was fully mature physically and it showed, which actually contrasted with the age of his character, who was earlier in high school) Jason Chan was already 30 when he played Cam in Ninja Storm— although, to be fair, Cam's age is never specified and it's not uncommon for a Sixth Ranger like himself to be an adult.
Executive Meddling: Originally all the villains were suppose to be vaporized by Zordon's wave in countdown (excluding Karone/Astronema of course). Fox Kids' BS&P forbade them to kill off the human villains.
This is why Wes and Jen didn't kiss at the end of Time Force. Although it's also why Eric survived.
Also in SPD, as far as making the Omega Ranger a ball of light when he wasn't morphed because the producers decided to spend most of the budget creating an all-original Zord/Monster fight for the finale.
Supposedly why Tommy wasn't killed off when his Super Sentai equivalent was, though also the reason why he came back as the Sixth Ranger a second time - a good example of Tropes Are Not Bad.
There seems to be some of this going on since Saban took the rights back. As we understand it, Nickelodeon is making Saban stretch each adaptation out to two seasons, or limiting seasons to 20 episodes thereby forcing Saban to take two years to do a full adaptation. Combined with longstanding contracts with Toei that don't let them skip any Sentai, it becomes kind of frustrating for fans as Rangers keeps falling further behind Sentai.
Fake American: From Ninja Storm onward, production took place in New Zealand, with mostly local actors trying their darnedest to pretend they didn't have Kiwi accents. Subverted by Xander in Mystic Force, who didn't even bother hiding his accent and was eventually handwaved as a native Australian that immigrated to the States.
In RPM, there's a fake Scotsman (Blue Ranger Flynn); also played by a Kiwi. Samurai has a Fake Mexican (Gold Ranger Antonio) played by a Thai/German!
And the even less serious Overanalyzed series by Girls Heart Geeks on Youtube.
Old Shame: Disney considered the entire series an embarassment. Also, though most actors are happy to have been a part of the franchise and embrace the fandom, there are some that consider their role this:
David Yost (Billy, the first Blue Ranger) hid from the fandom after the show ended, as he revealed in 2010 he was gay and that he quit the show after being thrown way too many homophobic slurs by the behind-the-camera staff and nobody would do anything about it. You can understand that he probably doesn't think of the fandom as an Old Shame, and the interview where he reveals this makes clear that he enjoyed the actual role of Billy, but the behind-the-scenes problems ruined the experience for him.
Amy Jo Johnson (Kimberly, the first Pink Ranger) also fell under this during the late 90's and early 2000's. At the time she was trying to make it as a Singer/Songwriter and didn't want to talk about it. In recent years she no longer considers her time with the show as old shame.
The only known actor who was known to have considered the show to be an old shame is Danny Slavin (Leo, the Red Galaxy Ranger), who only did the role to pay for law school. He nearly sat out the "Forever Red" reunion and forced production to use a Fake Shemp like they did with Aurico, but was talked into filming a few unmorphed scenes late in the process. He later also returned for Super Megaforce's version of the Legend War, despite having not acted in 10 years.
For a different variety of example, when Ron Wasserman recorded new versions of several songs from the series, he intentionally did not redo "White Ranger Tiger Power" because of the Unfortunate Implications of the song's title.