Continuity mistake: Josh is wishing Donna a Happy Thanksgiving - he is eating something out of his hand and has a blue book tucked under his arm, which flips from front to back from one shot to the next. When he starts talking to the Trekkie, it flips back again.
Inauguration: Over There - S4-E15
Continuity mistake: Bartlett is in the executive office in the residence watching four TVs at once. He hears a line in the black and white movie, a second later he rewinds it to hear the line again - he rewinds way too much and for too long, but once he stops the tape, it plays the line he wanted to hear again right away. He went too far back (for visual effect) than what in reality it would have taken.
Continuity mistake: Toby, Sam, and Amy are sitting at a table talking - Amy's eyeglasses are on the table in front of her - when Toby asks Charlie what's on the TV, the shot shows her glasses have rotated 180 degrees and her arms have noticeably changed position.
Continuity mistake: Toby and Leo are in Leo's office talking about the friendly fire incident - Leo's glasses are sitting on his desk in front of him. He then picks them up and moves them to the far left. A couple of shots later, he picks them up from the right and puts them on.
Continuity mistake: While Sam and Donna are listening to a TV report that Sam may be heading for Congress, the woman behind him has a phone receiver to her ear, with both hands on the phone. The shot changes and suddenly her right arm is down by her side, but in the next shot it is back in the first position.
Continuity mistake: While Amy is talking to Toby, the piece of shrimp in her hand gets larger and the level of champagne in her glass does down, even though she never drinks from it.
Continuity mistake: Bartlet agrees to have a photo op with a goat and says "let's do it right now" - as C.J. turns to her assistant, we can see the Pres is already half way down the hall, even though this would be impossible in real time.
Continuity mistake: When Donna is in Josh's office, picking up folders, she puts a blue one on top of the pile; the next split-second shot from behind her shows a brown folder on top of the pile - then she places a blue one on top of that.
Continuity mistake: In the Sunday Morning segment, at a White House meeting, a grey-haired woman is sitting at the table with her hand on her bottle of water - the next shot shows her hand several inches away, with no time for the change.
Inauguration: Over There - S4-E15
Continuity mistake: When the guys arrive outside Donna's building, Josh wears a tux and a long black coat with a white scarf. After Josh says, "The buzzer's not working", a few quick camera cuts occur, and as he says "Nah, I know women-" and turns, the scarf is missing. It is back as the cameras cut again and he says, "I know what they like." (00:33:30)
The Red Mass - S4-E4
Continuity mistake: Near the beginning of the show, Josh is talking about baseball while looking at some stapled political papers - the top one is folded back over the second one. As Donna asks "what is it?", the first page is falling free and Josh is only holding the second one, but he had no time to adjust them.
Continuity mistake: Sam is at the bar with Will Bailey. Will picks up his glass and tips it up to his mouth. The next shot from the other side shows him tipping it up to his mouth again.
20 Hours in America: Part I - S4-E1
Continuity mistake: Bruno and C.J. sit down in a meeting and are talking about women voters. When the shot is on Bruno, we can see C.J. is holding a black folder that is partially open. When the shot goes to her, though, she has her hands on the folder, which is opened on the table.
Continuity mistake: Newly hired Assistant White House Counsel Joe Quincy is looking over his new "office". He's told it is the office traditionally given to newly hired lawyers, and is known as the "Steampipe Trunk Distribution Venue". In prior episodes, Ainsley Hayes, the previous Assistant White House Counsel, was also given this office, but this space is significantly altered in size from the earlier appearances. Essentially, the length of the space has been cut in half and the intervening wall with door is gone. Yet the room is not newly remodeled. It's a basement space with old pipes and walls, etc. The makers simply shrank the set without explanation. (00:06:30)
Continuity mistake: Early in the show, Toby, Sam, and C.J. are at a conference table, talking about a concession speech. C.J. is holding a mug and scratching her hand, but as she turns and says "ooh, Mr. Lyman", her mug is suddenly sitting on the table. In the next shot, as she is talking to Josh, her hand is around the mug. None of these changes happen in natural time.
Continuity mistake: When Josh, Joe, and Donna are in Josh's office talking about the NASA report, Josh's pen is in his left side of the shirt pocket. When the camera cuts to them walking out of his office the pen is on the right side.
Evidence of Things Not Seen - S4-E20
Continuity mistake: In the closing minute, when C.J. Is trying to stand the egg on its end, the camera pans to the clock for DC, and it reads 12:00. But as she sits at the table, her watch reads 7:15. Then, in the next camera shot, zooming in onto the egg, you can see that C.J.'s watch reads 7:25.
Debate Camp - S4-E5
Continuity mistake: In season one, CJ's office was right next to Josh's office, but from season two on, it was at the opposite end of a long walkway that runs between several glass cubicles (one of which Donna uses). The later location for CJ was the press room for season one. The differences are not furniture, etc, but wall and door locations have been revised. This season four episode features a flashback where Donna visits the White House prior to Bartlet's inauguration, and she is led to her future cubicle. In this scene, we see the floorplan is not the earlier version, but the newer version. While the between-season changes can be excused as 'remodeling' that took place off-screen, this episode's arrangement can't make sense. (00:09:20)
Evidence of Things Not Seen - S4-E20
Continuity mistake: Will Bailey is wearing a military uniform for the only time in the show (as it is revealed he is a reservist Lieutenant in the USAF). On his uniform shirt there are three medal ribbons-bars. Those ribbon-bars (worn in the correct order from left to right) are as follows: 1. The Air Force Organisational Excellence Award Ribbon 2. The National Defence Service Medal Ribbon 3. The Air Force Training Ribbon. After the shooting incident outside the Press Briefing Room (where gunshots hit one of the windows), Lt. Will Bailey can be seen wearing his three ribbon-bars (incorrect) in the reverse order. Then following on in the two subsequent scenes Will's medal ribbons-bars are back in the correct order. (00:08:05 - 00:16:15)
Continuity mistake: When Josh is recapping his conversation with Jack to Donna, as he is walking towards the coffee pot he his putting a pen in his shirt pocket. When they turn to walk back to his office the pen has disappeared. (00:24:50 - 00:25:50)
Chosen answer: A really annoying innate lack of sense. My friends and family say the same thing all the time, and I'm endlessly trying to correct them. I think people just don't know any better and (ironically) couldn't care less that they're speaking incorrectly.