Continuity mistake: Early in the film, there is a scene where Uma Thurman and Colin Firth are in their bedroom and he brings her a cup of coffee. He places both cups on a tray then places it on the bed and frequently in the scene, the cups change from either being side by side, or one placed inside the other.
Character mistake: When the young boy is attempting to hack, Marriage Registry is spelled Wedding Registery. (00:10:56)
Factual error: When Emma and Richard decide to call off the wedding, to provide an excuse to evacuate the church they light a small fire to set off the sprinkler in the side room they are in, but the sprinklers also go off in the main area of the church, forcing all the guests to leave. Sprinklers are individually heat-activated, and one going off in response to a localized fire would not set off sprinklers in other areas.