Other mistake: In the episode "It's About Time!", near the end of the episode after they get back, when the camera zooms in on Phineas and Isabella, Isabella's face is gone - only her eyes remain, but after the camera zooms out her face is back.
Continuity mistake: In the episode "Greece Lightning" the veins in the eyes of the Candace mobile disappear and reappear when Candace is rolling down the hill.
Continuity mistake: In the episode 'One Good Scare Ought To Do It', when Phineas is carried into the air inside the haunted house, there is an aerial shot showing the Fireside Girls and Isabella, who is wearing a yellow sash like the other scouts as she shouts, "Phineas!" There are two problems here. First, Isabella wasn't wearing the sash before at the haunted house, until this particular shot. Also, between the shots before Phineas falls, her sash disappears, reappears and then disappears again. It reappears after Phineas falls, and Isabella says, "Quick, everyone! Sashes!"
Continuity mistake: In the episode "One Good Scare Ought to Do It", Candace arrives at Jeremy's house and is wearing a belt. (It's very clear as she yells "These are designer jeans!") After Susie's attacks, when Jeremy comes out Candace is on the ground with the dog still attached to her rear end and the belt has disappeared. In the next shot of Candace, the belt has returned.
Factual error: In almost every song characters are seen playing high notes and guitar parts on basses.
Continuity mistake: In the episode "Don't Even Blink", during the song segment, Phineas changes from playing the guitar lefty and righty several times.
Continuity mistake: In the episode "One Scare Ought To Do It," when the haunted house comes back, it is stuck to the Disinvaporator. The clock says 5 seconds left, but when it cuts to the closer shot of the clock, it lost 3 seconds, which means that 2 seconds are left.
Continuity mistake: One of Ferb's eyes is egg-shaped while the other is normal. Whenever he turns his head, the egg-shaped eye is always furthest away.
Answer: And Bart Simpson should be about 40 by now. Cartoon characters don't age in real time. And are you really counting summer vacation days in a show about children who build spaceships and a platypus who's a secret agent?
Brian Katcher