Despite trying to lighten the mood with some jokes, the last episode of 'ALF' might very well be the most depressing sitcom ending ever. Apparently they forgot that the 'com' stood for comedy!
Spoiler Alert: It wasn't continued.

Mike and Joseph talked about Lenny's jacket (from "Laverne and Shirley") during one of the 70s sitcom episodes. Joseph had forgotten that Laverne had to sew the 'L" on it for Lenny because when he got it, it only said "One Wolf" on the back! Poor, Lenny.

"Where Everybody Knows Your Name"

After two episodes and roughly 150 minutes, you might think Mike and Joseph would be tired of talking old sitcoms. Of course, if you thought that, you'd be wrong because the guys still have to cover sitcoms from the 80s!
http://www.whenitwascool.com/uphill-both-ways-22

"Prime Time" Part 2

Get your TV dinners ready and gather 'round - it's time for Joseph and Mike to conclude their "Very Special Episode" covering 70s sitcoms! 
http://www.whenitwascool.com/uphill-both-ways-21