Charlie mispronounces the location of the Red Sox's AAA team in Pawtucket, RI, as "PAW-tuck-it." It is actually "paw-TUCK-it" and, since most locals pronounce it "puh-TUCK-it" - with the "aw" part barely vocalized - this is how most people associated with the Red Sox organization pronounce it as well.
Zac Efron had a mole on his left cheek removed after principal photography wrapped in October 2009. In May of 2010 he did a re-shoot of the scene where he shows Tess his new boat. The mole is present for the whole film, then disappears.
The burn marks on Charlie's chest would not happen unless there was a flammable substance on his chest when he was defibrillated (and if this was the case you would have seen flames after defibrillation in the ambulance scene). Regular defibrillation does not leave any marks or scars.
When Charlie's EKG is 'flat-lining' (asystole), the paramedic defibrillates him. Defibrillation only works when there is pre-existing electrical activity in the heart, if the patient doesn't have any electrical activity ('flat-lining') resuscitation it achieved with drugs and CPR.