Factual error: The super glue (after sitting that long) wouldn't be wet enough for the earpiece to stick almost permanently to Marty's ear.
Factual error: The amount of dye from the bottle couldn't possibly make Marty's entire skin that deep a shade of blue.
Continuity mistake: The degree of blueness and orangeness of Wolf's skin and hair keep changing. Right before the first birthday party, he has bright orange hair. Yet when he leaves the birthday party, his hair is a duller orange. I don't think that hair dye wears off that fast.
Continuity mistake: At the premiere of Marty's failed movie, he is asking the president if he can explain his "breakthrough" on Big Fat Liar. The president raises his hand, and says "One chance, Wolf, that's all I'm giving you." It remains raised until two shots later (on Marty's line "strap on your seatbelt because you are about to be blown away,"), when it is suddenly resting at his side.
Continuity mistake: When Marty is talking to the studio's president about his 'incredible breakthrough' about BFL, Monty has her head leaned up against a chair. Marty continues talking when the camera cuts to a close-up of Monty. With no time in between shots to move her head, her head moves about 6 inches away from the chair.
Continuity mistake: At the very end, during the credits of Jason's 'Big Fat Liar' premiere, you can see Jason's mom over his shoulder wearing a spaghetti strap dress with a shawl around her shoulders. The shawl moves on and off her shoulder between shots.
Other mistake: When Marty Wolf is chasing Jason on the cart, as they drive through the winter set you can see the fake snow get on the camera lens.
Revealing mistake: After blue-Marty exits the pool he heads upstairs and when Jason and Kaylee spy on him dancing (with Mr. FB) Marty's entire body is dyed blue, but the blue only reaches to just above the bottom of his bare feet.
Continuity mistake: When Jason writes his paper, we see the handwriting of the title "Big Fat Liar", etc. Later, in the limo when Marty finds the story and when Jason is in Marty's office, we see the paper again and the handwriting differs.
Continuity mistake: Near the beginning, when Jason is done writing his paper he staples it. When he and Marty are in the limo, the pages are not stapled.
Continuity mistake: When Marty Wolf is washing his hair, before he dyes his beard you can see it is already a slight tint of orange.
Other mistake: Towards the beginning of the movie, directly after Jason's parents leave the house, Jason's sister's boyfriend drives up in an SUV to pick her up (the music in his SUV is blaring). The window on the passenger's side door is open. When Jason's sister opens the passenger's side door to the SUV, the already blaring music becomes louder, as if much more sound is escaping the vehicle. When she shuts the door after entering the vehicle, the music becomes quieter again.
Continuity mistake: When Marty Wolf pulls up behind "the Masher", an old lady hits Wolf's car and pushes it into the Masher truck. The old lady drives off while insulting Marty. The Masher drives around to crush Marty's car. When it cuts to Marty watching the Masher drive towards him, you see the old lady's car behind his again.
