An edited TV version shown on the Comedy Central cable network removes most of the drug references. For example, instead of "bag of weed," "bag of diamonds," was used, which made for a strange ending.
Also in the TV version, much of the music was replaced with music that exists elsewhere in the movie (notably "Taquela" was replaced during the scene where Cheech and Chong fix their van up).
As of December 2001, Comedy Central is showing a semi-restored version (edited for language, obviously) that includes all the drug use and original incidental music ("Tequila", and most notably, the awe-inspiring guitar solo by Steve Lukather). However, the statement by Peewee Herman to police is still missing: "I think they're Iranians!"
In the original theatrical release, Chong is lifted up into the space ship, then we don't see him again until he wakes Cheech. When the "bag of diamonds" version is shown on TV, it often includes a few minutes of Chong aboard the spaceship.