And Then There Were Fewer - S9-E1
Continuity mistake: When Diane Simmons tells Lois that she is the murderer, Quagmire has already left the manor with Stephanie's body in the boot. When Diane is walking Lois outside, Quagmire is seen again even though he just left. This has been cut from the DVD. (00:45:40 - 00:46:50)