Independence Day

Sept. 18: "It's Always Sunny in Philadelphia" (9 p.m., FX)

Production faced several hurdles this season including the broken back of actress Kaitlin Olson and the busy schedule of Danny DeVito, but nothing can stop this frequently hilarious comedy from taking on taboo topics. ... moreTopics such as Independence Day, which is explored in an episode that flashes back to July 3, 1776, are covered as the gang attempts to get the bar added to a historical walking tour. (FX)