Other mistake: As Dark Helmet says his line "Everybody knows that!", watch the crewman in white to Helmet's right. He starts to cover his crotch a beat too soon.
Spaceballs (1987)
Ending / spoiler
Directed by: Mel Brooks
Starring: Bill Pullman, John Candy, Rick Moranis, Mel Brooks, Daphne Zuniga, Joan Rivers, George Wyner
Lone Starr marries Princess Vespa. President Skroob, Dark Helmet and Colonal Sandurz survive Mega Maid's self-destruction and land on the beach on some planet... they are discovered by the apes from Planet of the Apes. "Oh $#!&, there goes the planet."
MissNiece
More mistakes in Spaceballs
Computer: This ship will self-destruct in exactly ten seconds. Counting down. Ten, nine, eight, six.
President Skroob: Six? What happened to seven?
Computer: Just kidding.
Trivia: President Skroob's name is an anagram of Mel Brooks' last name.
Question: Planet Spaceballs intends to steal all the air on Planet Druidia. Spaceball city and Planet Druidia are neighbors. When Megamaid explodes, her head lands on a beach on a planet that presumably has air. Why not steal the air on the planet inhabitated by apes? There's apparently no air shield. Additionally, the desert planet where Yogurt lives also has air and no air shield. Two other planets, in addition to Planet Druidia, that have breathable air.
Answer: The Spaceballs are a race of bullies, they only pick on planets they know have no defense, like Druidia. Yogart, like Yoda, was a very powerful being with mystic powers, While the planet of the Apes were highly intelligent and were most likely able to out smart a race of idiots.
Answer: In the context of the movie, the Spaceballs seem to hate Planet Druidia. So why not steal air from the planet they hate? In a more meta behind-the-scenes context... it's just better for the plot for them to target Druidia since it makes more sense dramatically and creates stakes for the story.
Answer: It also might stand to reason that the very fact that Druidia has a shield is what makes it viable. It almost creates a docking port for Mega Maid who was presumably designed for that very purpose. After all, what other purpose could a space maid with a vacuum possibly have?