McKay wants to give Sheppard a condensed description of what's going on and says "I'll give you the Cole's Notes," which he later corrects to "Cliff's Notes" for Sheppard's benefit. Cole's Notes are the Canadian version of Cliff's Notes.
Mannitol is a type of carbohydrate (specifically, a sugar alcohol). As a medication, it is used to help decrease intracranial pressure caused by bleeding from a subdural hematoma. It can also be used as a sweetener, for example, in diabetic-friendly food, as it is not absorbed well by the intestines.
First appearance of Amanda Tapping as Colonel Samantha Carter as a series regular and in the opening credits. Although she has appeared in three times already, two of those were in minor, inconsequential roles and the other was as Rodney McKay's hallucination of Carter.