Audio problem: When Steve is thanking Melissa for marrying Mark, the bride turns out to be Angela. Angela knocks Steve to the floor and grabs a gun from under her wedding dress. You can hear the sound of a hammer cocking but the gun turns out to be a hammerless automatic.
Visible crew/equipment: In the first plane scene, you see the toy plane take off, if you look at the first shot of it coming off the ground, you can see a shadow of a person and the headphones with the mic over the mouth. (00:06:05)
Continuity mistake: In the final wedding scene in the tent, both the father of the bride and the father of the groom walk in looking fresh and dry, not looking at all like they had just hopped off a jetski and been hit with a large wave.
Factual error: When Michael Douglas and his son (and others) are tied up in chairs, they pretend to fight and cut each other's bonds. The son says something like, "The one time my father came to Cub Scouts, I earned the Covert Action Merit Badge." But there are no Merit Badges in Cub Scouts; they are a part of the older Boy Scout program. (There isn't a "Covert Action" Merit Badge either, but that helped the movie along, so it's okay.)