Lynne, Charlie and Clare were in the woods because Jack ticked Clare off. Clare claimed that someone tried to attack her during the night and harm her baby. Jack thought it was pregnancy stress, and offered her a sedative. She got angry, and packed up to go to the beach. Charlie then ran after her.
Also, Hurley began taking a census and eventually asked Saywer for the plane's manifest. Sawyer (surprisingly) handed it over quite nicely. Hurley then realized that someone was on the island with them...but was NOT on the manifest. Turns out that it was the guy who kidnapped Clare and Charlie.