Archive Binge: The last 14 years of the show are up on the website.
Archive Panic: See above. 14 years worth of material.
Awesome Music: The Powdermilk theme, but also the saxophone-and-piano number that opens Guy Noir, and the theme song itself—so recognizable that people in the audience cheer at the very first note.
It started off as an Upper Midwest, folk music-oriented take on The Grand Ole Opry before heading off in its own direction.
On the flip side, The Vinyl Cafe clearly took inspiration from APHC but eventually evolved its own style. In the US, some public radio stations even air The Vinyl Cafe immediately following APHC.
Hilarious in Hindsight: Garrison Keillor's "I'm A Lutheran", from the 1990s, makes a lot of jokes about Episcopalians and how Garrison likes Lutherans more, Garrison Keillor is one of them (an Episcopalian) now.
Ho Yay: Occasionally between Dusty and Lefty, the cowboys. They tend to say "my partner", which makes people think of the newer version of "partner".
Keillor's red socks, invariably seen at the live shows. They're something of a personal trademark of his.
Leading to a joke among some fans that Keillor will only retire when "he runs out of red socks"
More Popular Spin-Off: Keillor hosted the weekday morning show on Minnesota Public Radio starting in 1969. After writing an article about the Grand Ole Opry in The New Yorker in 1974 he decided to try his own Saturday night live music variety show. He did both shows for a while, but the Saturday show was a big hit in Minnesota and became nationally syndicated, so Keillor quit doing the weekday show in 1982.
Never Live It Down: The "Penguin Joke" became a Running Gag because the first time Garrison Keillor tried to tell it on the air, he badly flubbed the delivery. They've been repeating his mistake word-for-word ever since.
Parody Displacement: the "Ketchup Advisory Board" commercials started as parodies of a series rather smug-sounding Merrill Lynch commercials from The '80s, and have continued long after their inspiration, much like Merrill Lynch itself, are mostly forgotten.
Spiritual Successor: The American Radio Company of The Air, Keillor's return to radio in 1989, was officially supposed to be one, but other than being New York-based, it was essentially the same show as APHC. When Keillor relocated back to Minnesota a few years later he gave up the pretense and went back to calling it A Prairie Home Companion.
Tropes found in the film:
Tear Jerker: Oh, God, yes...not least because of the thought of one's favorite radio show closing forever...