Here’s a short, 15 minute behind-the-scenes featurette about filming the Legend War scene, as well as soom footage from the first episode. This comes from a DVD/Bluray release of the first few episodes of Go-Kaiger.
As you can see, that really was a bunch of suit actors, and they managed to film all of that and the stuff for the promos that same day. And if you pay attention to the dates in this video, you can see that filming started within three weeks of the official annnouncement. I don’t know why it almost took a whole month before they started filming the rest of that episode, but that’s what happened. There are a few other surprises in their, but I’ll let you see them for yourself.
Credits to LukaMilfy for uploading this video.