Creator Backlash: Trent's actually not a fan of the band's now iconic Woodstock performance, considering it one of the band's worst. The myriad amounts of technical problems throughout the performance (Most famously Trent's keyboard breaking down halfway into Happiness in Slavery) probably had something to do with this.
Doing It for the Art: Considering how he doesn't mind piracy of his albums as well as licensing more recent work under a non-commercial Creative Commons license, it's obvious Trent just really likes making music.
Trent has said that With Teeth was the only album his label didn't complain about when it was delivered to them.
TVT Records was rather upset with Pretty Hate Machine because Reznor refused to be turned into Depeche Mode Part Two. Steve Gottlieb, TVT's founder, then tried to sabotage the recording of Broken and Trent's move to Interscope.
Official release of Closure on DVD was barred for so long that Trent just released the .ISO files of the DV Ds online himself.
Throw It In: A recording of Sean Beaven being bitten by Trent's dog Maisy appears in "Physical".
The drum solo in "Piggy" was a placeholder for a better drum solo later, but Trent liked it too much to lose it.
Trent once said that the guitar solo in "Ruiner" was so over-the-top in corniness that it had to be in the song. Ditto for the entirety of "Big Man with a Gun".
What Could Have Been: Reznor had considered doing quite a bit to promote Year Zero, including blowing up a building, arresting actual fans, and even staging an appearance of the Presence in real life. Of course, these never happened for various reasons.