The track shares some similarities with the early track "Rodox Video". Some even believe that "Rodox Video" is in fact an early version of "Peacock Tail".
Samples / Lyrics
The human voices that start around the 3:07 mark are a distorted sample of the Azan/Adhan or the Islamic call to prayer, probably this one in particular.
One of the voice samples could also be from The Elegants - Little Star. Here is an audio clip to demonstrate this theory where both tracks are overlayed and slowed down:
Trivia
Apart from being the most colourful feature of the peacock, it was also a figure used by Euclid to prove the Pythagorean theorem.[1]
The NBC Peacock, one of the most famous TV station logo in the USA, features the colours of the rainbow. Rainbows are frequently referenced in Boards of Canada's music (see: "Roygbiv" on MHTRTC)