Featuring the adventures of the jet packed, giant robot controlling secret agent latchkey boy Johnny Sokko and his....well giant flying robot as they battle various monsters from the nefarious Emperor Guillotine, a Cthulhu esque alien in a uber flamboyant gold suit and can chuck off his fingernails and cause a nuclear explosion with it. He also as a bunch of Nazi goons at his side called the Garogyle Gang who are lead by dudes like Captain Spider, a discount BBC Nazi, Doctor Botanus, the debut role of that actor who played Destro from the G.I. Joe cartoon and Dangor the Executioner the.....thing I guess

Based on a manga made by the guy who made Gigantor (No joke! He really did make both of these), Voyage into Space is a heartwarming tale for the whole family with gunfights where children get shot, train eating, Pharaoh headed robot with a shit tone of weapons given to a child by a enslaved scientist, Darn plants and Alien take over plots. It's Ultraman meets Gigantor...or if you were born 1996 onwards, The Iron Giant meets Pacific Rim (you guys have no childhood...even if I was born in the late 90's but who cares)

Although MGM owns the film, you can get it on FandangoNOW for 2.99 dollars rent so I guess Rifftrax's could sync it to that. It would make me happy to see it riffed because MST3K: The Return didn't unfortunately
https://www.fandangonow.com/details/movie/voyage-into-space-1968/MMV8619DD1A9FC97289F463F3E370EA1BB24
https://www.youtube.com/watch?v=zwz-2t5Rn-k
https://i.ytimg.com/vi/yayZr8fQJPY/hqdefault.jpg?sqp=-oaymwEXCNACELwBSFryq4qpAwkIARUAAIhCGAE=&rs=AOn4CLCQfOCaFroLBNvqgwqG5UrLoDAV8g