Trivia: While the two men are preparing for the raiders towards the film's end (as they lower the gates, etc.), the music playing is the same as that which accompanied the opening credits of "Monty Python and the Holy Grail."
Trivia: A few actors are in both Dawn of the Dead and Day of the Dead, playing different roles in either movie. Joe Pilato plays one of the guys at the dock in Dawn, and Rhodes in Day. Taso Stavrakis (aka Taso Stavrakos) is Sledge in Dawn, and one of the soldiers in Day.
Trivia: Despite popular belief to the contrary, the bright-red "pastel" look of the blood effects in the film was an intentional decision by director George A. Romero. He wanted the film to have a slight "Comic-Book Aesthetic", and thus chose an extremely bright hue of fake-blood in order to better contrast with the muted-gray look of the zombies.
Answer: One of the cops that was with Joe Plato (how much you have seen of them will depend on which version of the movie you, but I HIGHLY recommend the fan made/edited 'Extended Mall Hours' cut on YouTube) asked them for cigarettes. You'll notice that Roger and Fran lit up cigarettes as they were taking off, that's what Roger was laughing at.