The scene of Bud Abbott and Lou Costello doing their classic "Who's on First" routine is run continuously at the National Baseball Hall of Fame in Cooperstown, NY. It is regarded as the best version of this routine in existence.
The laughter that can be heard faintly in the background during the "Who's on First" routine belongs to the film crew and director Jean Yarbrough. After numerous re-takes trying to eliminate it, Yarbrough just couldn't get the crew - or himself - to stop laughing during the routine, no matter how many times they heard it. So he just gave up and left the giggling in.
One of the few films ever made about a show boat that depicts it correctly. A show boat was not a self-contained steamer but a barge, moved by another boat that was called a "tow boat" that was mounted behind the show boat, pushing it up and down the river. Of the three films of the musical "Show Boat," the first one -released by Universal in 1929 -got it right, but the 1936 and 1951 versions got it wrong.
The "Who's on First" sequence was added after the rest of the film was shot and edited. Universal executives thought the film didn't have enough laughs, so they wrote in "Who's on First," which Bud Abbott and Lou Costello had been performing for years on stage and radio, as well as a much shorter version in their first film, One Night in the Tropics (1940).
Although Bud Abbott and Lou Costello did not create "Who's On First," they copyrighted it as the "Abbott and Costello Baseball Routine" in 1944. "Who's On First" is generally believed to have been written by John Grant, who created many of Abbott and Costello's famous word-play dialogues, though a similar routine involving towns named "What" and "Which" appears in Cracked Nuts (1931) starring Bert Wheeler and Robert Woolsey.