Grant McFarland as Sensei and Lothor and Danny Sing as their past selves.
Jason Chan as Cam and Cyber-Cam.
Dawson Casting: Averted with Sally Martin and Glenn McMillan, who were in their teens at the time of filming. Played straight with everyone else in the central cast (special mention goes to Jason Chan, who was in his early thirties when production started).
Unfinished Episode: A crossover with Wild Force was planned as stated in an interview by producer Jackie Marchand, but due to production relocating to New Zealand and that it would be too expensive to bring in the cast, it was scrapped.
Very early materials suggested that the rivalry between the Wind and Thunder Rangers was supposed to play out a lot longer than it did (and possibly be the central conflict of the series, rather than a traditional villain), with kids even being encouraged to pick sides for themselves.
The Tori character may well have become a carbon copy of her Hurricanger counterpart (aspiring Idol Singer Nanami) had Emma Lahana, who auditioned for this role before becoming Kira in the following season, gotten the part instead of Sally Martin.
The entire series would have ended up being VERY different had the show not moved to New Zealand and changed production crews. Plans of Tommy serving as mentor, a Canon Foreigner Dark Yellow Thunder Ranger appearing (to help offset The Smurfette Principle), villains such as Scorpina and allies like Ninjor, and reappearances from various previous Rangers were all quashed the minute that production left the US and the writing staff was replaced. See here for more.
According to Doug Sloan, he wanted to avert The Smurfette Principle by doing a Gender Flip of one of the Rangers (most likely not Red or Yellow), but Disney vetoed it. Had this happened, then we would've seen the first female non-Yellow Ranger with a male Sentai counterpart.
As noted above in "Unfinished Episode", a Wild Force crossover. Interestingly, unlike with Reinforcements from the Future, they would've been able to use stock footage, as there was a crossover between the two sentai teams, so presumably the costs from moving the cast of Wild Force to New Zealand for filming wouldn't have been offset by what they could've saved using stock footage.
Word of God: Doug Sloan has said more than once that Tori's Arbitrary Skepticism in the premiere was meant to be taken as just that and never as an indication of a continuity reboot.