Star Trek IV starring Eddie Murphy and Steve Guttenberg
Steve Guttenberg in the (expanded) Bob role being all jealous/suspicious of Kirk romancing Gillian, then uncovering it all (spacemen from the future!) and eventually coming through and helping them and then waving goodbye to Gillian at the end 80s ET/Cocoon style.
Eddie Murphy in a cameo as one of the captains in the opening (who would briefly meet the big 7 at the end after the trial)
Back to The Future + Crocodile Dundee + Guttenberg/Murphy = the ultimate 80s SciFi movie!