Director Sydney Pollack guest-starred in three episodes as Will's father, who cheats on Will's mother (played by Blythe Danner) with a woman named Tina (played by Lesley Ann Warren).

Karen Walker's husband, Stan, is never seen.

Will originally had a partner in the original pilot, Higgins, but his scenes were deleted in the final draft of the script.

In "My fair Maid-y" (episode #1.12) Cyndi Lauper was originally cast as April, but was fired because she "just didn't work out".

Grace's middle name is Elizabeth.

Jack's full name is John Phillip McFarland. His drag name is Glen 125th (first pet's name + first street you lived on). His dog's name is Klaus Von Puppy (the one he got in "The Truth About Will And Dogs" (episode #1.10). He's also got a bird named Guapo.

In "To Serve and Disinfect" (episode #2.6), Grace found out that Karen made a fetish video called "Next to Godliness". Scenes from the spanking video were actually shot, but only the audio was aired.

Jack's Cher doll (first shown in "Gypsies, Tramps And Weed" (episode #3.17), is a $60,000 prototype of a doll that Mattel sold for a short time in 2001. Max Mutchnick currently owns that doll.

In the episode where Grace is going to meet an old High School crush, he says he is part of a group of artists showing their arts at the Zelman Gallery. Debra Messing's (Grace) real life husband is Daniel Zelman.

In "The Unsinkable Mommy Adler" (episode #1.13), Mrs. Adler walks in singing "Good Morning, Good Morning". Bobbi Adler is played by Debbie Reynolds, who sang the same song in Singin' in the Rain (1952), and also starred in The Unsinkable Molly Brown (1964).

Jarrod Emick read for the part of Will.

Alexis Arquette lost the part of Jack to Sean Hayes at the final auditions.

Nicollette Sheridan lost the part of Grace Adler to Debra Messing at the final auditions.

Megan Mullally was offered both Karen and the role of Carrie in "The King of Queens" (1998). She almost went with the latter role.

Early promotional spots for the show were ambiguous about Will's homosexuality since NBC didn't know how well the gay leading character would play.

Karen's characteristic high-pitched voice didn't really come into play until a few episodes into the show.

Rosario was a one-joke character in the first season, when Jack married her so she could stay in the country. The character became so popular, she was made a semi-regular.

In the episode when Grace married Leo, the music to which Will walked Grace up the aisle was the main theme from "Brideshead Revisited" (1981) (mini), composed by Geoffrey Burgon.

In "Flip-Flop: Part 1" (episode #6.15), Lyle Finster, played by John Cleese, calls Rosario "Manuel". Manuel was a character on "Fawlty Towers" (1975), written by, and starring, Cleese.

Jack's website www.justjack.com really does exist. It now redirects you to NBC's Will & Grace website, but at the time it was created, it was an actual web site created by "Jack." It included pictures and a letter Rosario wrote to the INS.

Originally Max Mutchnick and David Kohan pitched a straightforward couples comedy in which a gay man and his straight female roommate were supporting characters. NBC liked the supporting characters better.

Will's apartment building is at 155 Riverside Drive, Upper West Side Manhattan.

The Grace Adler Designs office is located in the Puck Building at 295 Lafayette St., south of Houston St.

The first episode of the eighth and last season was a live-aired episode

Due to Debra Messing's pregnancy during the sixth season, Grace did not appear in five episodes: 6.6 "Heart Like a Wheelchair", 6.21 "I Never Cheered for my Father", 6.22 "Speechless", 6.23/6.24 "I Do. Oh, No, You Didn't".

The commitment ceremony reading in "Coffee and Commitment" (episode #3.10), was written by episode writer Adam Barr (I) especially for the episode.

In "The Young and the Tactless" (episode #3.19), Will and Jack go to the opening of "The Atom Bar". Adam Barr was a writer and producer of the show at that time.

Trivia:

The first ads to promote the TV show played down the fact that Will was gay. NBC wasn't entirely confident about how that would be received by the potential audience.

In episode #13, "The Unsinkable Mommy Adler", Bobbi Adler (played by Debbie Reynolds) sings the song, "Good Morning, Good Morning". Debbie sang the same son in the classic movie, "Singin' in the Rain (1952)".

Debra Messing has a couple of titles to her credit. In 1986 she won the title of "Junior Miss" in the state of Rhode Island. In 2003 she was named "Best Dressed Woman" by TV Guide magazine. Debra is also well-educated having received a Master's Degree from New York University. And please don't send her any flowers or perfume. She's very allergic to them.

Eric McCormack is also a college graduate with a degree from Ryerson University's School of Theatre in Toronto. Eric was originally from Canada but has since received U.S. citizenship while also remaining a Canadian citizen. He obviously respects both of those honors. At the 2004 National Hockey League game he sang both the Canadian and U.S. national anthems!

There were five episodes where Debra Messing didn't appear. They were episode numbers 123, 138, 139, 140, and 141. She had a good reason though. She took a little maternity leave.

Karen Walker's squeeky voice was not an original trait. It didn't appear until after a few episodes.

Goofs for "Will & Grace"

Continuity: In episode 1:12, "My Fair Maidy", when Will introduces Grace to April, the pens in Grace's hair changes between shots.

Continuity: In the Pilot, when Jack and Will are playing cards with two other guys, Will deals Jack his first card two times between shots.

Continuity: In "Grace, Replaced" When Grace is freaking out, she has colored pencils in her hair. These pencils constantly shift positions and disappear/reappear.

Continuity: In "Poker? I Don't even Like Her" when Karen and Jack are doing helium hits in the hospital waiting room, they are using a purple balloon. The balloon disappears for a few shots, then reappears as a pink balloon.

Errors in geography: In "Love is in the Airplane", Will and Grace arrive at London Heathrow airport, but the sign behind them points to the "Restrooms" not "Toilets".