And Star Trek is patterned after Forbidden Planet.
Also SAAB had a lot of Galactica similarities, right down to the burning flag at the end of the initial surprise attack. Its just inescapable that you'll find similarities real, coincidental or just imagined.
IMO the most blatent "Rip Off" in a long time was The Island staring Ewan Mcgregor. It was a blatent (and I believe unauthorized) remake of "parts: the clonus horror".
http://www.imdb.com/title/tt0078062/reviews
If youve seen both, you'll know this is the poster child for movie Rip-Off's.