Continuity mistake: When Frank and Charlie crash Thanksgiving dinner at Frank's brother's house, his sister-in-law Gretchen says that she'll go set two more places at the table. However, she never leaves, and a minute later, they're all walking into the dining room with the correct amount of places set.
Continuity mistake: Charlie and Frank arrive at W.R. Slade's house to crash Thanksgiving dinner. When the camera shows a front shot (looking out at them from inside the house) Charlie is standing behind Frank; whenever the camera switches to a rear shot (camera looking into the house) Charlie is standing next to Frank. The error is repeated three times.