American Humane's Film & Television Unit monitored this film. The Wedding Crashers is a Screen Actors Guild (SAG) production, and therefore it was required to provide American Humane's Certified Animal Safety Representatives on-set access whenever animals were used. During pre-production of the film, American Humane's Film & TV Unit received a copy of the script and the daily call sheets. American Humane's Certified Animal Safety Representatives carefully reviewed these materials to determine whether any scenes or situations appeared to put animals at risk. American Humane's Certified Animal Safety Representatives were then on the set to ensure the animals remained safe throughout production.

Although American Humane monitored a scene that involved quail, the birds did not make it into the theatrical release. The birds may appear on the DVD version. The trainers worked with Maryland's Department of Natural Resources to obtain a permit for the release of 47 quail at the plantation on which they were filming. This large plantation was very suitable for release as it provided trees, grass, and brush for the birds, which are indigenous to the area.

In a brief montage, John and Claire (Rachel McAdams) ride bikes down a country road to a pasture of sheep. The sheep lived on a nearby farm and the owner agreed to let the couple ride in the pasture as the camera man filmed the action.