The drum loop passes quickly between the right and left channel. When wearing headphones, it sounds like it's spinning around your head. When reversed, it spins the other direction.
Samples the famous Conet Project which compiled various recordings of "number stations" and shortwave radio transmissions. This starts at about 48 seconds into the song.
Mike and Marcus have admitted to having an interest in shortwave radios in their formative years, and stated that some of their really early (i.e. pre-BoC) music was made by chopping up recorded shortwave transmissions. They have never explicitly mentioned these so-called "numbers stations", but those who have heard such transmissions can testify to similar qualities in some of their music: grainy synthetic transmissions that swing between perky, simple tunes or mysterious noises, and children's voices, or even sheer aural terror.
There is also some reversed guitar parts that swirl into the mix near the end of the track, which some have said may be from a 12-string.
Brian Palan mentioned that the voice reading numbers in "Gyroscope" on Geogaddi isn't from the film Mercury Rising but that it's taken from a recording on the Conet Project boxed set. The Conet Project documents "numbers stations" which are found all along the shortwave radio spectrum. They're used by the world's intelligence agencies to send secret messages to agents in the field. 
"Yeah for me it would be the track "Gyroscope". I dreamed the sound of it, and although I've recreated dreamt songs before, I managed to do that one so quickly that the end result was 99% like my dream. It spooks me to listen to it now."