This is the first Gokaiger episode to feature a returning Super Sentai cast member. Hashimoto Atsushi returns to his role as Ozu Kai, aka MagiRed. The first armament robot, based on MagiRed's Giant Robot/Dragon form is revealed. I don't know how many former Sentai cast members there might be in the series, but I doubt Atsushi will be the last. What is heavily in question is weather they will be able to continue bringing back the original actors. Magiranger is a relatively recent Sentai series, airing in 2005. So it isn't as hard for Atsushi to play the same role. Essentially, the older the Super Sentai series, the more unlikely it is actors will be able to reprise their roles. In Kamen Rider Decade, a series that similarly had a theme of going back through it's series history, utilized other actors to play the roles of other Kamen Rider heroes - even when they did seemingly have access to the original actors. Seto Koji, who played Kurenai Wataru (Kamen Rider Kiva), appeared in the first episode of Kamen Rider Decade, but only played an evil version of the character, while a young boy played the role of Wataru. This might have been because of possible production overlap, since the series Decade aired right after Kiva ended. (These are year-long shows, with usually nearly 50 episodes for each series.) Whatever the case - wether they might need to utilize replacement actors in future episodes of Gokaiger, I'm still happy to see they are making the effort to bring back the original actors.
Oh, and I also wanted to mention that earlier this week I put up a profile for the villain Damaras. Also, at the bottom of this post, you'll find a single image to be added to MagiGreen's profile.
You can find these images added here: MagiRed Profile
You can find these images added here: Gokaiger Robots
You can find this image added here: GokaiRed Profile
You can find this image added here: GokaiYellow Profile
You can find these images added here: GokaiGreen Profile
Gokaiger Group Image
You can find this image added here: Gokaiger Group Images
Previous Sentai Powers
You can find these images added here: Previous Sentai Powers