To prepare for their roles, and despite being warned against mixing with the students, the cast of the Deltas in "National Lampoon's Animal House" (1978) (except John Belushi, who was in New York City working on "Saturday Night Live") accepted an invitation from some girls to a real frat party at the University of Oregon's SAE house. The real fraternity members treated them with hostility, and a brawl ensued, started by James Widdoes when he threw a cup of beer at some drunken football players. Widdoes ended up losing a few teeth, and Bruce McGill received a black eye. When Belushi returned to the set and learned of the fight, he had to be physically restrained from seeking revenge. Although accidental, this real-life incident proved emblematic of the members and character of Delta House.
The actors who played the Deltas harassed the actors who played the Omegas off-screen as well, to keep up the feelings of animosity between their characters. Mark Metcalf changed his hotel room to the one above McGill's, where the Delta actors partied every night, so his anger at their noise would help him get into character. McGill actually stole the piano from the hotel's lobby and moved it into his room so that the group would have music.
John Landis and McGill staged a scene for reporters visiting the set, where Landis pretended to be angry at Bruce for being difficult on the set. Landis grabbed a breakaway pitcher and smashed it over McGill's head. He fell to the ground, and pretended to be unconscious. The reporters were completely fooled, and when Landis asked McGill to get up, he refused to move.
McGill's role of D-Day was written for Dan Aykroyd, and based on his motorcycle-loving personality. According to John Landis, "Saturday Night Live" producer Lorne Michaels threatened to fire Aykroyd if he took the role. (IMDb)
Happy Birthday, Bruce McGill!
