- Ability over Appearance: It was originally intended that Chris O'Dowd's cop would be American, but everyone was so enamored with O'Dowd's native Irish accent that it was decided that he keep it.
- Billing Displacement: The posters for the film ran with the bridesmaids theme, depicting all five of them (plus the bride) which was why Chris O'Dowd (Officer Rhodes) doesn't appear, despite playing a more important character than Wendi McLendon-Covey (Rita) or Ellie Kemper (Becca).
- Cast the Runner-Up:
- Rebel Wilson auditioned for Megan before being cast as Brynn.
- Rose Byrne initially also auditioned for Lillian, but later took the opportunity to read Helen. Byrne was eventually chosen as the nemesis because she wasn't a comedian as Paul Feig feared the character would be "coming out to be too arch if we had a funny woman doing it.
- Creator Couple: Ben Falcone, who plays Air Marshall Jon, is married to Melissa McCarthy (Megan.)
- Deleted Role: Paul Rudd was to appear as a man who Annie goes on a blind date with, but the scene was cut from the final film.
- Deleted Scene: There was originally a scene where Annie goes on a blind date with a character played by Paul Rudd, who seems perfect until he goes insane when a child ice-skates over his finger.
- Fake American / Fake Brit: Australians Rose Byrne and Rebel Wilson play an American and a Brit respectively.
- Hey, It's That Place!: Ted's house's exterior is the same one used as Kelly Taylor's in Beverly Hills, 90210.
- Hide Your Pregnancy: Maya Rudolph was pregnant with her third child during the filming of this movie. Most of the clothes she wore had a belt on them to distract from her stomach.
- Name's the Same: The name of Lillian's husband-to-be is Doug(ie), like the groom in the first Hangover movie.
- Orphaned Reference: More like an aborted Brick Joke; during Annie's meltdown at the bridal shower, she sarcastically asks if Lilian and Helen are going to ride around Paris on bikes with baguettes in the front baskets. A deleted scene found on the DVD and Blu-ray release shows a mortified Annie watching an online video them doing just that.
- Reality Subtext: This was Jill Clayburgh's (Annie's mom) last film, as she was secretly fighting leukemia.
- Star-Making Role:
- Melissa McCarthy was primarily a television actress before this movie. Her film career and star status skyrocketed after this and hasn't stopped since.
- Wendi McLendon-Covey was best-known as a supporting player outside of Reno 911!. Her raised profile from this film led to her getting cast as the lead in The Goldbergs and allowed her to work as a full-time actornote .
- Rose Byrne gained a lot more attention after appearing in this and broke into increasingly bigger pictures.
- Stillborn Franchise: Universal was considering developing a sequel without the involvement of Kristen Wiig, when she stated in an interview she and Annie Mumolo weren't planning a sequel and were "writing something else". The rumored sequel would've likely focused on Melissa McCarthy's character's wedding in the Bahamas without Wiig's involvement, which she considered "a terrible idea" in an interview.
- Uncredited Role: Jon Hamm chose to go uncredited as he felt his presence on the credits would signify a more serious film, seeing as he, as an actor, is not generally recognized for appearing in comedies.
- What Could Have Been:
- Working Title: Maid of Honor.
Trivia / Bridesmaids