Much of the scene where Andie crashes Ben's "boys night" was improvised. Kate Hudson had the idea to toss the platter of veggies at the guys seated at the poker table. Donald Petrie, the director, knew she was going to do this but the actors in the scene were truly surprised.
Kate Hudson improvised plastering Matthew McConaughey with kisses during the scene where she introduces the new dog. This is why McConaughey looks genuinely surprised.
A lot of the scenes were improvised, e.g. the scene with the "family album."
There were an estimated $14,200,000 worth of jewels lent to the film.
When Andie and Ben go to see Sleepless in Seattle (1993), according to the commentary, Kate ad-libbed two quotes: "I've always wanted a man like Tom Hanks" and "You can't watch Meg Ryan for two hours and not be thinking about another girl."