Revealing mistake: As Dr. McNamara is marking Megan O'Hara for her breast reconstruction surgery you can see the lower line of her prosthetic "removed breast" from her mastectomy on her left side. It is not the surgical scar from removing the breast, that is visible about an two inches higher closer to where the nipple should be. My aunt had a mastectomy, I know there should be no scar here.
Continuity mistake: When Matt and Henry are driving after getting high, they accidentally hit Cara Fitzgerald with Henry's car. Matt then slams on the brakes, and you can see black skid marks. After the car stops and they get out to look around, several different camera angles show no skid marks at all behind the car now.
Deliberate mistake: While Megan O'Hara is undergoing breast reconstruction surgery, as the camera pans a close-up side angle view of her face you can see she is wearing make-up, specifically eye make-up, which is strictly prohibited in a surgical sterile environment in the United States, especially in pre-scheduled surgeries. (00:23:50)
Answer: "All I Know" by Art Garfunkel.