Other mistake: When Mrs. Bennet is thanking Col. Forster for his kindness to Lydia for taking her to Brighton, the camera pans out while Mrs. Bennet is still speaking. If you look at Mrs. Bennet and Col. Forster from that shot, it shows Col. Forster speaking to Mr. and Mrs. Bennet at the same moment. Mrs. Bennet could not possibly be speaking at that time.
The Secret of Management - S4-E9
Other mistake: The coffee mug that Cadbury gives Bill is empty.