http://hochi.yomiuri.co.jp/entertainment/news/20111031-OHT1T00033.htm?from=yol This article is mostly old info, but there's a bit of new stuff.
Producer Utsunomiya said that with this movie they were aiming for the true meaning of "collaboration." Ohba says he thought the Gokai cast was better-looking than him but they're also kind and serious. Ozawa said that Ohba was quite manly and he learned a lot from him.
About the plot:
Gavan rescues the Gokaigers from the worst prison in space and they fight alongside one another. Ohba will transform into Battle Kenya and Denjiblue. An enemy known as "Gavan Bootleg" will also appear.