The lyrics are a similar vein to "Roll With It" in that it encourages the listener to get on with their life without being specific about how this is to be achieved. The song samples the drums from Johnny Jenkins' version of Dr John's "I Walk on Gilded Splinters". The title may be a reference to the line in "Hey Jude" by The Beatles, "So let it out and let it in, hey, Jude, begin". Noel described the song as "the closest we came to sounding like a modern day Beatles" in the 'Lock the Box' interview found on the DVD in the special edition of Stop the Clocks. The lyrics appear to be directly influenced by R. L. Sharpe's poem "A Bag of Tools". The fact that the same poem had also influenced Bobby and the Midnites' "Book of Rules" prompted a music journalist to quip that Oasis could not even plagiarise originally. The song bears a striking resemblance to "The Seeker", a song by The Who, both in tempo and musical structure. They are so similar that the vocal melody of one of the songs is almost interchangeable with that of the other.
The song, along with B-side "(As Long As They've Got) Cigarettes in Hell", also embodies the psychedelic feel which the band experimented with on the album. It couples this with an acoustic guitar chord sequence. "Let's All Make Believe", the second B-Side is considered by many to be one of the best Oasis B-sides. Some people believe the lyrics of this song to relate to the cracks that began forming in the group at the time (see below), for example: "So let's all make believe/that we're still friends and we like each other."
Due to the departure of guitarist Bonehead and bassist Guigsy in the early recording sessions for Standing on the Shoulder of Giants, the track features only Liam Gallagher (vocals), Noel Gallagher (rhythm guitar, bass guitar, lead guitar) and Alan White (drums).
Oasis were looking for replacements for founding members Bonehead and Guigsy and while Bonehead was quickly replaced with fellow Creation signing and former Heavy Stereo frontman Gem Archer, Guigsy proved harder to replace. Thus the trippy video for "Go Let It Out" had to be filmed with Noel on bass, Archer in Noel's role as lead guitarist and Liam in Archer's role as rhythm guitarist.
The b-side "Let's All Make Believe" has recently been included in several lists as a 'hidden gem', such as Q magazine placing it at number one on its list of '500 best lost tracks' and at 4 on its 'list of songs to download this month - January 2006.' Q magazine said in the description 'If Standing on the Shoulder of Giants had contained this track, it would have probably got another star'.
In the "lock the box" interview, Noel considers "Go Let It Out" to be "head and shoulders" above any other songs he had written during this time, and its "up there with some of the best things I've ever done."