"Matte Kudasai" (Japanese: 待って下さい) literally means "please wait". The original release of Discipline featured only one version of "Matte Kudasai", with a guitar part by Robert Fripp that was removed from the track on a subsequent release of the album. The latest versions of the album to be released contains both versions of the song – track 3, "Matte Kudasai", without Robert Fripp's original guitar part; and track 8, "Matte Kudasai (alternative version)", with the guitar part included. 
"Thela Hun Ginjeet" is an anagram of "heat in the jungle". When it was first performed live, some of its lyrics were improvised around an illicit recording made by Robert Fripp of his neighbours having a vicious argument when he was living in New York; this recording is featured on the track "NY3" on Fripp's solo album Exposure. While the track was being recorded for the Discipline album, Adrian Belew, walking around Notting Hill Gate in London with a tape recorder looking for inspiration, was harassed first by a gang and then by the police. On returning to the studio, he gave a distraught account to his bandmates of what had just happened to him. This account was recorded by Fripp without Belew's knowledge as well, and is featured on the Discipline version of the track (as well as almost all live versions), in place of those earlier lyrics that were based on Fripp's New York recording.
Later versions of Discipline featured this design by Steve Ball.
Live versions of "Elephant Talk", "Indiscipline", and "Thela Hun Ginjeet" included partial vocal improvisation during spoken-word parts. One such example can be found in the 13 August 1982 performance, which, as of 12 August 2014, was still available for download in both MP3 and FLAC formats from DGM.
The back cover features the statement, "Discipline is never an end in itself, only a means to an end". King Crimson purchased the rights to use a variation on a copyrighted Celtic knot design by George Bain on the LP cover. In later releases, it was replaced by a knotwork designed by Steve Ball on commission from Robert Fripp. Ball's design is also used as the logo of Discipline Global Mobile, the music label founded by Fripp, which has become the label for King Crimson, Fripp, and associated artists.
Discipline reached number 41 in the UK Albums Chart and received mixed to positive reviews. John Piccarella's review in Rolling Stone praised the talent and artistry of the four musicians of King Crimson, particularly Belew and Fripp's "visionary approach to guitar playing", but criticized the "arty content" of the album itself, concluding "Here's hoping that, unlike every other King Crimson lineup, this band of virtuosos stays together long enough to transform all of their experiments into innovations."Robert Christgau described the album as "not bad--the Heads meet the League of Gentlemen."
Greg Prato's retrospective review in AllMusic gave unqualified approval of the album, particularly applauding the unexpectedly successful combinations of Fripp and Belew's disparate playing styles. According to him, "the pairing of these two originals worked out magically."
Pitchfork ranked it at number 56 in their list of the "Top 100 Albums of the 1980s".
^Fripp, Robert (2001-01-09). "Chop Em Out Mastering Olympia". Robert Fripp's Diary. DGM Live. Retrieved 2017-07-29. We are listening to the alternative version of "Matte" with RF on sustained guitar lines and solo. This is the version included on the original 1981 "Discipline" release, and was later replaced by the original pre-overdub minimalist mix on releases after 1989. In Island studios, recording and mixing of the album completed, Adrian & I agreed that something more was needed for "Matte". He left it to me to come up with something, flew home, but when he heard my contribution wasn't convinced. I agree. This new re-release gives us the opportunity to include both versions, in accordance with a suggestion made a while ago on the Guestbook.
^Bain, George (1951). Celtic art: The methods of construction. London: Constable Press.
Bain, George (1973). Celtic Art: The Methods of Construction. Dover Publications, Inc. ISBN0-486-22923-8.
^Ball, Steve (1 October 2001). "Saturday September 29". Steve Ball diary. SteveBall.com. Retrieved 29 February 2012