Coming Home - S4-E1
Continuity mistake: When Joey and Pacey are on the boat Coming Home, look closely at Pacey's hair under the cap he is wearing. It is longer/thicker hair, and appears to be layered somewhat on the sides and back of the neck. A little later when Joey and Pacey have docked in Capeside and are getting off the boat, Pacey's hair is suddenly cut very short/close to the head, and does not look like it did under the cap on the boat. (00:00:50 - 00:05:05)
Audio problem: When Dawson's father hands the baby to Joey, so he can take a picture of her and Gretchen before the Prom, you can hear a noticable "Ahhhhhh" in a female voice from the background, that sounds very much like Dawson's mother. But this wouldn't make sense, as Gail had just gone off to find her shears and cut roses for the corsages.
Coming Home - S4-E1
Deliberate mistake: This scene between Dawson and Jen in his 'dark room' was shot in a distinctive red light. However, in reality there was no red light during filming, the effect was added later during post-production. (00:19:25)
Falling Down - S4-E2
Plot hole: When Dawson goes over to Joey's house to talk to her about Pacey's school problems, he mentions that Pacey had missed that entire day of school. Joey apparently didn't know this, as she is surprised at the news. Since Joey and Pacey are closely involved - wouldn't she have noticed his absence at school that day already? Surely she would have noticed Pacey missing for an entire day of school.
A Family Way - S4-E5
Revealing mistake: During the scene when Dawson and Gretchen are talking on the bridge, two couples walk by in the background. An older couple passes from left to right, and a younger couple walks from right to left. The younger couple is a woman with blonde, curly hair wearing a green top and beige/white skirt, and a guy wearing a green or blue top and white pants. During the same scene, the same younger couple again walks by in the background from right to left two more times. Then the older couple walks by again from left to right. Then one final time, the younger couple walks by yet again for a fourth time from right to left. Guess they were using the extras a lot that day. (00:27:15 - 00:28:50)
Coming Home - S4-E1
Continuity mistake: When Joey and Pacey are talking on the dock just after arriving back in Capeside, Joey's hair changes instantly from being swept behind her right shoulder and behind her back, to sitting in front of both shoulders.
Falling Down - S4-E2
Plot hole: Mrs. Valentine almost fires Joey, after discovering that she lied about knowing the Owens. Drue steps in and saves Joey's job by claiming he did see the Owen boy. But Joey keeps her job throughout the rest of that season. Since the Owens were said to be in Paris only until the 1st of the year - wouldn't Mrs. Valentine have found that Joey lied about knowing them as soon as they returned to Capeside? Surely Mrs. Valentine would have mentioned Joey to the Owens; thinking she was their good friend, and because she was new on staff at the Country Club they were members of the board for. And once she found out Joey had indeed lied, why did she not fire her at that point?
Continuity mistake: When Jen and Jack are talking in her room, Jack asks "Have you finished your applications yet?" Jen is rubbing her hands together in front of her. But the next shot, suddenly Jen's arms are stretched back behind her. Too sudden to be a realistic transition.
Coming Home - S4-E1
Plot hole: Dawson and Jen are in a small 'darkroom', developing photos and speaking at a normal level. This darkroom is located just behind the main stairs, and very close to the living room where Dawson's parents are 'getting busy'. Therefore, the parents normally would have heard their voices so close to them, and known they were in the house and not been so surprised by them.
Falling Down - S4-E2
Continuity mistake: At the end of the episode, when Pacey is telling Joey about his school problems; her hair changes dramatically between shots. Just as she says, "Whatever it takes, we're gonna fix it", her hair is blown back off her right shoulder, away from her face with only the hair ends resting on her shoulder. The next shot of Joey, as she says, "I'm not going anywhere without you", her hair is suddenly down in front of her right shoulder, and close to her face again. When Pacey asks her, "Joey?" and she replies, "Yeah?", her hair is still fully down by her face on the right side, in front of her right shoulder. But then the next shot of Joey when she says, "I'm not that much smarter, Pace", her hair is suddenly swept far back off her right shoulder, away from her face with the hair ends resting on her shoulder again. It looks like they filmed this scene two different ways, and edited it together.
Admissions - S4-E17
Continuity mistake: When Joey and Dawson are talking at her house before the party, there is a shot of Joey with her hair swept back behind her right shoulder, and the ends curled up as if blown by the wind. She says, "Doing what?" Then the next shot of Joey, as she says "I know," her hair is suddenly completely down around her face, in front of both shoulders, and not curled up on the ends or wind blown. Then the next shot of Joey when she says, "Oh it was nothing, it was great," her hair is once again swept back behind her right shoulder, and curled up on the ends from the wind.
Plot hole: After Drue has spent the night at Jen's house, Grams explains to Jen that she had a nice talk with Drue right after Jen left for school. But this doesn't make sense, because why would Jen have to be at school a certain time, and Drue not go to school at the same time or at all? His attendance at school would have been required as well.
Coming Home - S4-E1
Plot hole: This scene reveals that Joey has brought Dawson a special gift from her sailing trip with Pacey. It's a brick from the foundation of Ernest Hemingway's home in the Florida Keys, symbolic to 'build the foundation of a friendship' between her and Dawson. In reality, it's highly unlikely that anyone would have allowed Joey to damage a foundation wall by prying out a large-sized brick; and steal it from the premises of a famous, historic home and landmark. (00:36:15)
Coming Home - S4-E1
Revealing mistake: This scene of Dawson and Joey in the parking lot of the "Dive-In" was not really filmed in the same location. The show only had the location of the "Dive-In" for a limited time, and had to film all other related scenes in the parking lot of the studio in Wilmington, NC. Any scenes that don't show water in the background; and are just palm trees, lighting etc. were actually shot several weeks later in the parking lot, which was recreated to be part of the beach at the "Dive-In". (00:33:30)
Continuity mistake: When Jen and Grams are arguing in the kitchen, Jen says "Why don't you donate to someone who cares". At this point, Jen turns to face away from Grams. But the next shot shows Jen suddenly turned towards Grams, facing her. Later in the scene when Grams says "Why don't you take the time to fill out a couple of your college applications", Jen is turned towards Grams. But the next shot suddenly Jen is facing away from Grams again. Apparently this scene were filmed two separate times, and edited together.
Admissions - S4-E17
Plot hole: When Pacey and Joey are unloading the groceries from the car for her party, Pacey makes a remark that he has to go to Joey's garage to get a dolly to haul in the charcoal. But Joey's house doesn't have a garage. During the entire series; there has never been a visible garage on their property, and the large blue truck is always parked out front in the open.
Plot hole: During the 4th act of this episode, Dawson and Joey spend an evening together as friends. When they are walking out of the coffee shop, they suddenly laugh and switch their coffee cups as if they had each others. This doesn't make logical sense, as they wouldn't know they had the wrong coffees without tasting them first, and if they had tasted them already inside the shop or knew they had the wrong coffees, they probably would have switched the cups then without waiting until they got outside. And usually the coffee is handed to the individual who ordered it, so they wouldn't be switched.
Other mistake: During Pacey's phone call to Joey at the end of the episode, Pacey lies about being on a fishing trip and mentions having caught a "91 pound marlin" which is a pretty big fish. This doesn't make sense for him to say that, as a fish that large would be noticably missing when he and Doug returned home. And they wouldn't have likely thrown a fish that large back into the sea. It would reveal he was lying if he returned home without the fish.
Factual error: When Joey and Pacey go down to the Basement to talk, they catch Dawson and Gretchen kissing on the basement couch. They are lying on the bottom cushion of a couch raised above the floor. But when Pacey is talking to Gretchen about it in the kitchen during dinner, he says something about "Catching her and Dawson making out on the Basement Floor". He definitely uses the word floor, but Dawson and Gretchen weren't down on the floor - they were up on the couch. (00:23:25 - 00:26:05)
Answer: It's only explained once in the series. Jack says to Andie "I tried to start kindergarten without you", meaning Andie was smart enough to start school early.