During the dice game, Lou's tie is on for the close-ups, but off for the long shots.
Accustomed to performing for live audiences, Abbott & Costello "never did anything the same way twice," as editor Philip Cahn complained. "No two takes were exactly the same," said director Arthur Lubin. Continuity errors were almost inevitable.
When Herbie surprises the chef from behind, the chef grabs a relatively clean wooden rolling pin. However, in the next shot, the rolling pin is covered in dough and flour.
At 52 minutes, Herbie turns on a radio and the sound comes out instantly. This was not possible in 1941 because the radio used vacuum tubes, not transistors. The vacuum tubes took several seconds to warm up before they could produce any sound. The transistor, invented in 1948 was only used in a radio in 1955 when the Japanese Sony Corporation introduced the first transistor radio which had instant warming, thus instant sound.
In the song "Boogie Woogie Bugle Boy," during Patty Andrews' solo, she claps her hands at the end of the line, "He can't blow a note 'til the bass and guitar's playing with him," but the slap sound effect misses her gesture by full beat.