In the elevator, Desmond and Claire are going to the 15th floor - 15 is one of Hurley's numbers.
26 min in - In the line of people walking through the jungle there is a little boy carrying a toy stuffed bear. That bear and presumably the same boy makes their 1st appearance in season 1.
Sawyer talks of Claire "drinking Locke's Kool-Aid". This is a reference to the Jonestown massacre in 1978. More than 900 people died in a mass murder-suicide by drinking cyanide-laced punch at the order of cult leader, Jim Jones. It is a common misconception that they drank Kool-Aid, in reality it was grape 'Flavor Aid'.