After Charles bails out of marrying Henrietta and is feeling terrible about it, and the others aren't exactly impressed with him, Tom pipes up that if he really wasn't sure about marrying her, then he was right not to go through with it. Fiona, who throughout the film has been responding to all Tom's remarks with an irritated "Bugger off, Tom", looks as though she's about to say it again — then she just touches him on the shoulder and says gently, "Quite right, Tom."
Designated Hero: Carrie cheats on her fiancé twice and Charles ditches his girlfriend at the altar, but we're supposed to root for them to get together.
Designated Villain: It seems that the writers had Charles reconcile with his least favorite ex, the shrewish Henrietta, because he would have looked like a jerk dumping any of the nicer ones or Fiona.
Even worse, she's actually quite nice at the third wedding, apologizing for how she acted at the second one. Presumably, this is why he decided to give their relationship another try, so he ends up looking like a jerk anyway.
Memetic Mutation: To this day, "# Of _______ And A _______" or even just "# Of_______" is recognizable as a play on this movie's title.
Narm: Andie McDowell doesn't exactly give the most electrifying performance of her career here. Especially "Is it still raining? I hadn't noticed."
Relationship Writing Fumble: A sizable number of fans wish Charles had ended up with Fiona, after the moving scene where she reveals to him that she's loved him since they first met.
Strangled by the Red String: Charles declares his love for Carrie at their third meeting when they've only slept together twice and haven't even seen or spoken to each other in the months between the three incidents. Then, despite sufficient time to get over his feelings, he ditches his fianceé at the altar to get together with her. They have a grand total of five meetings in the film, but this is supposedly enough for them to decide they want to spend the rest of their lives together.
Tear Jerker: Matthew reading Funeral Blues at the funeral.