Black Sheep Hit - They have a knack for this. "Creep," their first hit, is more of a starting point for their work than anything else- they evolved past it fairly quickly. Their highest-charting song since then, "Bodysnatchers," is considerably more raucous and punk-influenced than the rest of In Rainbows.
"Lotus Flower" (which, thanks to its memetically famous video, became quite big online) sounds almost nothing like the band's prior work.
Creator Backlash - Radiohead grew to hate their first hit song "Creep" because people would show up to their concerts exclusively to hear it, acting indignant until they played it and leaving immediately afterwards. They continued to play it reluctantly, usually stating how they have no respect for the people that wanted to hear it right before. They eventually cut the song from their setlist for a long period of time, and wrote "My Iron Lung" as a reaction ("This/This is our new song/Just like the last one/A total waste of time/My iron lung"). They even asked every single band who were playing on the Pyramid Stage (which they headlined) at Glastonbury 2003 if they'd be so kind to perform it so they didn't have to (the duty taken up by Moby instead). Now it seems that they've warmed up to it, since they played "Creep" several times in 2009.
It's sort of weirdly ironic that "Creep" and "My Iron Lung" are, at the time of writing, the only Radiohead songs in the Rock Band catalogue. (Creep is on-disc for the first game, My Iron Lung is DLC.)
Thom Yorke also dislikes another early hit, "High and Dry", saying "It's not bad... it's very bad." Radiohead hasn't played it for a decade.
There's a much more minor example, in that every member has expressed regrets about Hail To The Thief, but it's more that it's not as good as it could have been rather than that it's bad.
Creator Breakdown - Thom Yorke's periods of depression largely inspire the bleak tone of much of his work. Most notably, his trouble coping with the attention that the band received after the success of OK Computer largely caused the much more challenging music in Kid A and Amnesiac.
Promoted Fanboy: Just about all of the collaborators on "TKOL RMX 1234567."
Jonny himself is a promoted fanboy for Krzysztof Penderecki, with many of his classical compositions inspired by Penderecki and performing with the elderly composer at Sacrum Profanum 2011 and even collaborating together on an album (48 Responses to Polymorphia being Jonny's own addition).
Throw It In: A missed cue led to the electric guitars in "Fake Plastic Trees" coming in late. It made the song more powerful so they left it.
The title of "Packt Like Sardines in a Crushd Tin Box" stemmed from a typo.
What Could Have Been - The band veered into Kid A's avant garde electronica as a reaction to the overwhelming praise garnered by OK Computer's more accessible, anthemic art-rock. Fans of the latter sometimes find themselves wishing their favorite album *hadn't* been one of the most acclaimed of all time.
The B-side "Cuttooth," well-liked among the community, was very nearly included on Amnesiac, but held off at the last minute for reasons unknown.
There were plans to release Kid A and Amnesiac as a double album.
Due to the band often performing new songs live before they record them on the album, there are a lot of sometimes drastically different versions of certain songs floating around. Some more notable examples include the various forms of "Nude" played for a decade before it was finally recorded, and the original version of "Videotape" which ended with a rather epic rock-out instead of the album version's drum loops.
Word of God - Averted by the video for "Just": the final line that the man lying in the street says is not subtitled, and the cuts between odd camera angles make lip reading impossible. The band have refused to say what the line is. Lip-readers making the attempt have said it seems to be "I like banana yoghurt".
Thom himself stepped in with the true lyrics of "Pearly" ("Darling use me") when he saw that fans were hearing it "Daddy hurts me."