The subject of the very popular "TV Bloopers and Practical Jokes" show for many, many years, thought it worth starting a thread where people can place links to their favorite TV show bloopers. There may be some mild language in them along the way.
Mary Tyler Moore Show - final season:
http://www.youtube.com/watch?v=O4XHXeiMRSk
Star Trek - original series (bear in mind, the doors were supposed to slide sideways on entry)
http://www.youtube.com/watch?v=JZAkGfJY05k
Countdown:
http://www.youtube.com/watch?v=FyNAdLJpWxc
Prisoner (aka Cell Block H), two lots:
http://www.youtube.com/watch?v=FdBrImQ5gm8
http://www.youtube.com/watch?v=vUR7Bcay334
Happy Days - number one:
http://www.youtube.com/watch?v=oS7XXiqH_4E
..and number two:
http://www.youtube.com/watch?v=K9w-msjh ... re=related
The Golden Girls:
http://www.youtube.com/watch?v=aIrw_YzO ... re=related
Frasier (a little lengthy, but great for fans)
http://www.youtube.com/watch?v=v-VuPbXE ... re=related