"This Land is Your Land" was used and performed by Garrett and Caron because they didn't have to pay royalties.
The production budget was less than $20. One Carl's Jr value meal, loose change to throw on the ground, one 7-11 Slurpee, and gas was all that was paid for during the shoot.
The first six days of the film were shot in one day. The final day, two year later, was actually two years later.
The global warming video can still be found on YouTube.
The grocery store scene was filmed on Mary's camera that can be scene on global warming day.