At a convention of television critics during the summer of 2005, executive producer Chuck Lorre confirmed that the show's opening tune is performed by studio musicians and not by actors Charlie Sheen, Jon Cryer and Angus T. Jones (who merely lip-sync the lyrics). One of the actual crooners is singer and voice-over artist Elizabeth Daily.
Rose was originally written off near the end of season four by having her move to London, because Melanie Lynskey had landed a part on the FOX pilot, Drive When that show was canceled, she was allowed to return to Two and a Half Men.
It's never mentioned as to what Judith does for a living. Herb is a pediatrician, Alan is a chiropractor, Charlie is a jingle writer (and later a children's composer), Evelyn sells real estate, Berta is a housekeeper, Kandi is an actress, and Rose sits on the board of directors at her father's bank.
Charlie Sheen does not play the piano on the show. He is dubbed by composer Grant Geissman, who plays offstage while Sheen fakes it on a dead keyboard. With composer Dennis C. Brown, Geissman also writes the music for the jingles Sheen's character creates.
Alan's cell phone's ringtone in the beginning of the series is Ludwig van Beethoven's "Für Elise". In later seasons, his ringtone is a possibly covered version of Fifth Dimension's "Up, Up, and Away." One of the show's running gags is Alan's cell phone ringing at unexpected times and places.
Watch the opening theme song during the later seasons. During the song, Angus T. Jones appears as young as he was during the First Season, but at the end of the song in later season, he "morphs" into the age he is for that particular season.
Filming had to be interrupted during season 7, when Charlie Sheen checked himself into rehab in February 2010. Sheen's time in rehab was related to a domestic violence incident with his wife Brooke Mueller on Christmas Day 2009 after which he was charged with felony menacing, third degree assault, and criminal mischief.
During the making of Dharma & Greg, another Chuck Lorre production, he had a film editor named Charles Harper Yates. This is the reference to selecting Charlie Harper as the name of Charlie Sheen's character.
In the opening credits, where the theme song of the show is played Jake (Angus T. Jones) is usually seen growing from a young child to what he currently looks like according to the episodes. However in the later episodes of season 9, Walden's hair becomes shorter and his beard disappears at the end of the theme song indicating his recent new look in the show.
In 2012, Angus T. Jones (who plays Jake) appeared in a video for the Forerunner Seventh Day Adventist Church in which he talked about his religious beliefs and observances. He also criticized his TV show on religious grounds, saying, "Jake from 'Two and a Half Men means nothing. He is a non-existent character. If you watch 'Two and a Half Men,' please stop watching 'Two and a Half Men.' I'm on 'Two and a Half Men,' and I don't want to be on it. Please stop watching it; please stop filling your head with filth. Please. You know, people say it's just entertainment. The fact that it's entertainment...do some research on the effects of television and your brain, and I promise you you'll have a decision to make when it comes to television, and especially with what you watch on television. It's bad news....I don't know if it means any more coming from me, but you might not have heard it otherwise. Just watch out. Watch out. A lot of people don't like to think about how deceptive the enemy is. He's [the devil has] been doing this for a lot longer than any of us have been around. So we can't play around. There's no playing around when it comes to eternity." Jones subsequently apologized to the cast and crew for any "indifference and disrespect" he showed to them (although, notably, not for insulting the show).
For a short period of time, Walden used the false name of Sam Wilson. Samuel Wilson (September 13, 1766- July 31, 1854) was a meat-packer from Troy, New York whose name is purportedly the source of the personification of the United States known as "Uncle Sam".