Corrected entry: In the "Whale of a Tale" scene: When Kirk Douglas is singing the second verse of the song, the other sailors start laughing before he gets to the punchline of the joke in the song.
Corrected entry: If you look at the sub in its side shots, the lights on the side appear to be a smiling face.
Correction: How is that possibly trivia?
Corrected entry: In the scene where Kirk Douglas is singing "Whale of a Tale," the guitar he's "playing" doesn't appear to have any strings.
Correction: The guitar does indeed have strings. They are visible several times, when the light hits them at just the right angle.
Corrected entry: The title is impossible! For starters, a league is a horizontal distance measurement, ie. length, not depth. In addition, I'm not exactly sure, but I believe it would be a length of about two and a half times around the earth. So, it would be utterly impossible to travel that far under the sea even if it was a depth measurement.
Correction: The title refers to the horizontal distance travelled while under the surface of the sea, rather than the depth under the sea.
Corrected entry: A squid does not propel itself at speed tentacles first, but head first.
Correction: The first films of giant squid, captured in the Sea of Japan in 2013, show them doing just that. It's all about how they attack prey and the positioning of their eyes, but they can and do travel at speed tentacles first.
Correction: There two possible reasons for this. 1) They're sailors, it's not impossible they've been drinking and are just laughing. 2) Kirk Douglas seems to only know that one song. By that point the voyage had gone on for over 3 months. It's possible he had performed it before and they were laughing knowing what was coming. It could even be a combination of both those.