In the movie
While flying in the Eagle 5 with Lone Starr, the two of them get a call from Pizza the Hutt demanding 1,000,000 spacebucks. Soon afterward, King Roland of Planet Druidia asks Lone Starr to rescue his daughter, Princess Vespa, from Dark Helmet. Lone Starr and Barf agree to do so in exchange for 1,000,000 spacebucks.
Once Lone Starr gets in position, he and Barf line their ship up with Vespa's and in the process decide to jam Spaceball I with a giant jar of raspberry jam. Fighting ensues within Starr's ship with Lone Starr poking fun about how she's a Druish Princess (a play on the archetype Jewish Princess) and Vespa playing that stereotype perfectly. They then enter Hyperactive (parody of Star Wars' Hyperspace) with Dark Helmet using "Ludicrous Speed" in an attempt to catch up.
The Eagle 5 crash-lands on the Moon of Vega, leaving Lone Starr, Vespa, Barf, and Dot Matrix to try and survive the harsh desert land. Barf tries to act as a mediator between Lone Starr's and Vespa's arguments. Eventually, Dark Helmet kidnaps Vespa, so Barf and Lone Starr travel to Planet Spaceball and rescue her.
After Lone Starr rescues Planet Druidia, he and Barf receive news that Pizza the Hutt ate himself to death, meaning that they no longer owe him any money. However, after they return Vespa to King Roland, Lone Starr turns down the 1,000,000 spacebucks, as an expression of his love for her. He and Barf open a fortune cookie from Yogurt after getting gas for the Eagle 5, which reveals a message from him. Yogurt informs Lone Starr that the mysterious pendant around his neck is a royal birth certificate, proclaiming him a prince. With this news in hand, Lone Starr proposes to Vespa, and she accepts. Barf attends the wedding as Lone Starr's Best Man (well, Best Mawg, technically).
- In the Russian translation of the movie "a mawg" was rendered as "chelobakka", a portmanteau of words "chelovek" (a man) and "sobaka" (a dog) also spoofing the name Chewbacca.
- In the scene where Lone Starr rants about Vespa's bratty behavior, Barf forgets to unbuckle his seat belt before getting out of his chair, and exclaims, "Oh! That's gonna leave a mark." John Candy performed this gag on the spot.
- Spaceballs marked the fourth time that John Candy worked with Rick Moranis, the actor who portrayed Dark Helmet. First, they both became regular cast members in SCTV. Then, they both played secondary roles in Brewster's Millions. Later, Moranis landed the male lead role of Little Shop of Horrors, and Candy made a cameo. Unlike all those other works, though, Moranis and Candy never share a scene.