Eddie Murphy was originally supposed to have starred in "Star Trek 4: The Voyage Home", instead of Catherine Hicks. Murphy was supposed to be a professor concerned with UFO's who spots the de-cloaking Klingon ship at the Super Bowl. Apparently, everyone else was to be convinced the ship is a half-time special effect while Murphy believed it was real. Paramount declined this script for two reasons: firstly, they didn't want to combine their two most profitable franchises ("Star Trek" and "Beverly Hills Cop"), and whilst deciding on their plans, Murphy had signed on to do "The Golden Child" instead.
You can also catch actor "Charles Dance" as Sigourney Weaver's character Lt. Ripley's love interest in Alien 3 as the Physician in the movie. But sadly his character becomes one of the victims later in the film.