The weird vocal effects used during the "Black Lodge" sequences were achieved by having the actors learn their lines backwards. The result was then played backwards, meaning the lines came out forwards, but sounded bizarre and otherworldly.
In the 2014 book Reflections: An Oral History of Twin Peaks by Brad Dukes, Jules Haimovitz (who was the president and COO of Spelling Entertainment while Twin Peaks was on) says that during the show's run, he got a call from the financier Carl Lindler demanding to know who killed Laura Palmer. Lindler told Haimovitz that he was asking not for himself but for then-president of the United States George Bush, who was in turn asking for Mikhail Gorbachev, then the leader of the U.S.S.R.
The pattern on the floor of the Black Lodge is an enlarged version of the pattern on the floor of the lobby of Henry's house in Eraserhead (1977), also directed by David Lynch. The pattern also appears on Leland Palmer's sport coat at the end of the first episode, as he dances with Laura's picture.
The character of Bob came about when David Lynch had a sudden image of set decorator Frank Silva hidden in Laura Palmer's room. Lynch filmed the infamous shot of Silva hiding behind Laura's bed without any idea of what he would use it for. Later, when filming a shot of Sarah Palmer (Grace Zabriskie) sitting up and screaming, Lynch noticed that Silva's reflection was visible in the shot, purely by accident. Lynch then came up with the idea of BOB as an other-worldly spirit, giving birth to the series mythology.
Anne-Marie Sakowitz: Do you know that you just charted us on a course through unprotected waters?
Steve Zissou: Yeah, we're taking the shortcut.
Anne-Marie Sakowitz: But it's outside I.M.U. jurisdiction. There isn't any protection.
Steve Zissou: I know, honey. Look at the map. We go your way, that's about four inches. We go my way, it's an inch and a half. You wanna pay for the extra gas?
Supposedly Cousteau and his cronies invented the idea of putting walkie-talkies into the helmet. But we made ours with a special rabbit ear on the top so we could pipe in some music.