Character mistake: After Ben tells his story about his first encounter with the ghouls, Barbara begins her story. She talks about the ghoul Johnny was joking about. She tells Ben that she wanted to apologize. She states, "I said good evening, and he grabbed me." If you go back to that original scene, you'll never hear her say "Good evening." (00:29:40)
Character mistake: A space traveler would not be "going to Orion." The major stars in Orion vary in distance from the earth from 243 to 1,360 light years. Orion is only a constellation as visible from Earth; once you get away that far, the stars would not be in the same alignment as they are from Earth. They would have been going to a specific star, probably Bellatrix at 243 light years, as Taylor mentions being at 320 light years.
Suggested correction: I'm not sure what scene you're referring to, but I never heard anyone say they went to Orion. Taylor says they're on a "planet in orbit around a star in the constellation of Orion. That could be Bellatrix." To Taylor, who is from Earth, the star is still in the constellation of Orion.
I agree with your take, but I still think it could be interpreted as Orion's stars all being in close proximity. And I would hope they would know about the 320 - 243 light year issue.
Character mistake: Pygar says to Barbarella, "An angel has no memory." If that's true, how does he recognise Barbarella's touch, her name, his name, his nest, everything?