The title is from the song "Ah! Sweet Mystery of Life" from the operetta by Victor Herbert, 'Naughty Marietta'.
Tom breaks the fourth wall only with his expression.
Horror author Stephen King would take the whole ledge pursuit idea down a more sinister path in his 1976 short story The Ledge. The tale was again published as pert of King's anthology, Night Shift, in 1978.
The title is a reference to the love song "Ah! Sweet Mystery of Life" (1910), but there is no apparent connection to the film's plot. There is no romantic subplot in this film.
As cartoon shorts transitioned from being part of cinematic programs to TV mainstays for kids, they became more slapstick and less structured, as in this example. It plays solely for laughs, and the background detail, while still evident, has become less 3d accurate in presentation.