Mind Games - S4-E16
Revealing mistake: When Jen and Jack are having coffee at the coffee shop, Jen walks outside and turns to bang on the outside window of the store to get Jack's attention. When she hits the window, you can tell it isn't a real window made of glass. It's obviously some sort of plastic, as it flexes too easily and moves too much to be a real store window. This was probably done to make the window safer for the actors during this scene.
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.
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.
Eastern Standard Time - S4-E18
Plot hole: When Jen introduces Joey to her father in his office, she calls her "Joey Potter from Capeside". But later when they are at dinner, Jen's father suddenly refers to Joey as "Josephine" which seems strange as he wasn't told that was her legal name, and only those who know her well would know that. Joey is not necessarily a nickname only for Josephine, so it wasn't just a logical deduction.
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.
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.
Continuity mistake: When Joey and Pacey are talking at the table on the Promboat after the 'brutal breakup'; her arms keep changing position too quickly between shots. As Joey says, "You break my heart into a thousand pieces," her right arm is folded across her, and the right hand is resting on her left sleeve just below the bare shoulder. The next shot, from behind Joey you can see her right hand still gripping her left shoulder, but the sleeve is further up and ruffled on that side. Then just before she says "Just leave me alone", the next shot again shows Joey from the front; and suddenly her left arm is raised up, hand by her face, and the right arm is down on the table with the hand curved up in the air. As she says "Just leave me alone"; her left arm is still up and hand resting by her face, and the right arm is laid sideways across her, hand on elbow. Then the next shot of Joey shows that suddenly her pose has changed; and her left arm is raised up diagonally, hand across her right shoulder, and her right arm is still laid horizontally across her, hand by her elbow. All of these transitions are far too abrupt and fast to be realistic.
Revealing mistake: When Doug stops Pacey on the street to talk to him, Pacey turns to face Doug (and the camera). You can see at this point, the microphone sticking out from Pacey's upper shirt. (00:04:25)
Plot hole: When Pacey and Andie are talking at the Senior Party, she excitedly mentions that he will be in the Caribbean that Summer. Pacey says that Andie would be in Florence, Italy. This doesn't make sense, because at that point in the episode, none of Andie's friends knew she was returning to stay in Italy. In fact, later during the graduation ceremony, Andie is talking to her brother Jack. He is the first person she tells the news to, and even says, "I haven't told anyone else this". So how would Pacey know the night before that Andie had decided to stay in Italy longer? (00:30:45 - 00:37:25)
Continuity mistake: During this scene towards the end, Bessie insists on putting lipstick on Joey for Graduation. She dabs it on quickly, and there appears to be a noticeable smudge or mark on Joey's upper right lip from the lipstick. But the next shot of Joey, the lipstick suddenly appears normal and perfectly applied, and the smudge is gone. (00:33:40)
Deliberate mistake: During this scene when Dawson and Joey are getting ready to graduate, the actor James Van Der Beek asked to ad lib his dialogue. He did, and what ended up on the air was his improvised version of the lines that had been written in the script. (00:39:30)
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.
Continuity mistake: Right before the graduation service, Dawson is joking with Joey to get her mind off her speech. The wind has blown Joey's tassle so it's caught partly on her left ear facing the camera. But in the next shot of her, the tassle is suddenly hanging normally in front of her ear. She hadn't appeared to move her hands.
Revealing mistake: When Grams is in the Kitchen with Jen and Jack, her sweater isn't buttoned right. When she walks close to the table you can see that the bottom edges of the front of the sweater don't match. It appears to be about one button off-one side is higher than the other. (00:26:35)
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.