I did like the yellow jumpsuit comment from Leo though.
Which was undermined by the fact that "his" April later appeared in her own version of a yellow jumpsuit.
It sounds fun, although a little fanwanky and totally non-canon (similar to the "Forever Red" Power Rangers special they did several years ago).
I don't think there's any reason to assume this is non-canonical. For one thing, I don't know if they're going to make any more of the new series after this, so if this is the last thing they do, nothing's going to contradict it. And most of what happened was reset at the end, though I guess there's still Hun's new mutation to contend with. But given that alternate realities are already an established part of the show's continuity, I can see this fitting in.
And whoever said "Forever Red" was non-canonical? It's not as if Power Rangers has ever had a particularly cohesive canon to begin with. It's contradicted itself plenty of times.
As for the original voice of Shredder, wasn't it the guy who played the father on Fresh Prince of Bel-Air?
Yes, James Avery was the original Shredder. He's done a lot of voice work, including the original Jim Rhodes/War Machine on the '90s Iron Man cartoon and Sir Bryant in the syndicated The Legend of Prince Valiant. Strangely, he was later replaced in all three of those roles by Dorian Harewood, who doesn't even sound like him. And not all at once, but several years apart. I always wondered what the deal was there.