Son of a bitch! George Brent and other Warner Bros. stars forget their lines (image: George Brent ca. 1940)
The Warner Bros. outtakes from the studio's 1939 and 1940 productions (see below) feature a whole array of movie stars and supporting players not getting things quite right while the cameras were rolling. Perhaps the biggest "star" – i.e., the one featured the most – in the montage is George Brent, who curses right and left after not getting his lines right in several scenes. But not to worry; "son of a bitch" is the strongest exclamation we get to hear. (I'm assuming stronger fare is to be found in the outtakes' outtakes.)
Besides George Brent, the Warner Bros. bloopers montage has Paul Muni joking around while forgetting his lines during the making of We Are Not Alone; Miriam Hopkins having her dramatic moment in The Old Maid ruined by a young maid (as in housemaid) who trips and lands face first on the floor; and a blonde Jane Wyman unable to remember her goddamned line.
Pat O'Brien's flying toupee and other Warner Bros. mishaps
Pat O'Brien is another frequent presence in the outtakes. While filming Torrid Zone opposite Ann Sheridan (whose voice you hear, feeding him lines), O'Brien complains "son of a bitch, with this cigar I've swallowed eighteen mouthfuls." Later on, opposite George Brent, O'Brien swallows another mouthful while filming (I believe) 'Til We Meet Again. The result is a hoarse delivery of the fateful question, "Seen him around where?" And it's Pat O'Brien's toupee that goes flying at one point.
In addition to George Brent, Pat O'Brien, Miriam Hopkins, Jane Wyman, and Paul Muni, among the other actors featured in the montage are Joel McCrea and Brenda Marshall in Espionage Agent, Merle Oberon and Binnie Barnes (rolling her "r's") in 'Til We Meet Again, Ann Sheridan at some sort of Dodge City promo, Flora Robson and Jane Bryan in We Are Not Alone, Priscilla Lane, Eric Blore, May Robson, Humphrey Bogart, Marie Wilson, Thomas Mitchell, Allen Jenkins, Ronald Reagan, Alan Hale, clumsy cowboy Dick Foran, and James Cagney dancing with George Raft and George Bancroft during the making of Each Dawn I Die.