Continuity: Warren Schmidt's home address is listed as 5042 Farnam Street for most of the film, but at the end, when he gets the letter from the nun, the address on the envelope is listed as 5402 Farnam Street (although, admittedly, it is not unheard of for mis-addressed letters to be delivered).
Continuity: The position of the purple napkin when Schmidt is being fed the soup in bed.
Continuity: During a conversation between Schmidt and his daughter, his sandwich changes from a fairly sparse one to a somewhat plumper one. It subsequently returns to its original thin shape.
Continuity: During the conversation between Warren Schmidt and his daughter after the funeral, his right hand changes position on the glass of milk between the shots.
Continuity: The broccoli changes position between shots on Schmidt's plate during Ray's speech.
Continuity: The vacuum cleaner behind Jeannie during Warren's lunch moves between shots.
Continuity: The sky during Warren's confrontation with Ray alternates between sunny and overcast.
Errors in geography: When Warren is in Colorado, there are Nebraska license plates on cars parked in driveways.
Continuity: When Warren uses a payphone to call Ray, he is asked to press "3" to erase his message and re-record. He actually presses the # key.
Continuity: Also in the payphone segment, a pickup truck that has begun leaving a parking lot in the background in the wide shot is nowhere to be seen in the background a split-second later when the shot goes to close-up.
Continuity: When Warren Schmidt leaves Roberta Hertzel's house to go and sleep in his RV, the RV is noticeably tilted to the right due to its being parked on the side of the street. When he is inside, it is perfectly level.
Continuity: Throughout the retirement dinner, Warren Schmidt is wearing a small gold pin on the left lapel of his suit jacket. When he arrives home from the function and takes the phone call from his daughter, the pin is missing.
Continuity: In the opening scene, while Warren Schmidt is sitting in his office watching the clock, the telephone, and especially the phone cable, repeatedly change positions on the desk between shots.
Continuity: The seasons change back and forth, between winter and summer. Sometimes the trees are bare, but in the next scene, they're full again. At the beginning of the movie, the trees are bare and it's gray and cold. Yet, two weeks later he leaves on his trip and it's summer all of a sudden.
Audio/visual unsynchronized: After Warren returns to find his wife sprawled on the floor, the vacuum is seen to be unplugged. Despite this, a vacuum is still heard running loudly.
Continuity: When Warren returns home from his journey to Denver which has presumably taken several weeks, you can see a vase of fairly fresh-looking flowers at the top left of the shot.
Errors made by characters (possibly deliberate errors by the filmmakers): In the shot where Warren and Helen pull up to the restaurant for Warren's dinner there is a sign that announces Warren's retirement dinner. On the sign the word "retirement" is spelled "retirment."
Errors in geography: Scenes showing the University of Kansas are obviously not filmed in Kansas. The real Kansas buildings have red roofs with beige brick.
Revealing mistakes: The key Helen picks out on her way to the car is not a car key.