As Pacey and Dawson walk into Dawson's house, Pacey's shirt is cream colored with vertical stripes down the front. Once they have entered the house, he is in a totally different shirt, a white one with horizontal and vertical stripes.
In the first episode, the first sign that we see says Capeside High, Home of the Wildcats and it is in black and orange but a mere five seconds later, if you look carefully, you can see students walk past another sign that clearly says Capeside High, Home of the Minutemen and the colors are blue and yellow, as are the jackets of the jocks throwing the football around.
The mascot of their high school is the Patriots. But in some early episodes you can see posters hanging in the school that say Go Wildcats. That is the mascot of New Hanover High School in Wilmington which is where they filmed school scenes in the first season before moving locations to UNC-W.
In the pilot episode, as the four enter the movie theater, Joey raises her arms to pull her shirt up and a wireless microphone box is visibly clipped to the back of her waist.
Boom mic is visible while Jen is sitting at the kitchen table talking to her grandmother.
When Jen is in the kitchen with Grams, you can see a boom mic fall down on the top hand of the screen very visibly.