Many of the lives of our survivors seem to have been interconnected before they even boarded
Flight 815:
- Ana-Lucia and Hurley are connected through Big Mike, after Hurley was rescued. Big Mike was Ana-Lucia's partner, but interrogated Hurley after he made detective (Ep: 4x1, The Beginning of the End).
- Charlie saved Sayid's childhood friend, Nadia, from a mugger (Ep: 3x21, Greatest Hits).
- Locke's father, Anthony Cooper, was the con man, going by the name of Tom Sawyer, who conned Sawyer's mother out of money, which caused Sawyer's father to shoot his mother and then himself. Sawyer wrote a letter to Mr. Sawyer and later took his name and his mode of operation in conning (Ep: 3x19, The Brig).
- Sawyer's long con, Cassidy, later became friends with Kate (Ep: 3x15, Left Behind).
- Paulo and Nikki saw Boone and Shannon arguing in the airport (Ep: 3x14, Expose).
- Claire finds out that Christian Shephard (Jack's father) is her biological father, though she doesn't know his name. Jack and Claire, at this point, are unaware that they are half brother and half sister (Ep: 3x12, Par Avion).
- Desmond sees Charlie playing a guitar, but recognizes him because Desmond is doing that part of his life over (Ep: 3x8, Flashes Before Your Eyes).
- Libby and Desmond spoke at a coffee shop and she gave him her late husband's boat (Ep: 2x23, Live Together, Die Alone).
- Kelvin Inman is who had Sayid torture Sayid's commanding officer in the army (Ep: 2x14, One of Them). Desmond spent three years in the hatch with Kelvin Inman (Ep: 2x23, Live Together, Die Alone).
- When Eko argues with Charlotte at the airport (Ep: 2x21, ?), Libby steps in to ask if everything is okay.
- Mr. Malkin, Charlotte's father (Ep: 2x21, ?), is the psychic who Claire went to, and who was so adamant that Claire be on Flight 815 (Ep: 1x10, Raised by Another).
- In Australia, Sawyer walks into the car door of the car Ana-Lucia is in. (Ep: 2x20, Two for the Road)
- Ana-Lucia meets Jack's father, Dr. Christian Shepard, in the bar of the airport where she works. She goes to Sydney with him, but decides to go back home, which put her on Flight 815. (Ep: 2x20, Two for the Road)
- In a flashback that was deleted (but can be seen on the Lost Season One DVD), the pilot speaks with Claire in the airport coffee shop and tells her that everything is going to be okay.
- Locke returns Rose's pill bottle when it rolls away from her in the airport. After the crash, Rose knows all along that Locke had previously been in a wheelchair. (Ep: 2x19, S.O.S.)
- Libby was in the Santa Rosa Mental Hospital at the same time as Hurley. (Ep: 2x18, Dave)
- Sayid's Nadia was the owner of the house that Locke inspected. (Ep: 2x17, Lockdown)
- In the background of one of Charlie's flashbacks (Ep: 2x12, Fire + Water) is a sign that says "Widmore Construction". The pregnancy test that Sun uses is made by "Widmore Labs" (Ep: 2x16, The Whole Truth). Also, Michael worked in construction. We don't know the construction company name, but I'd be willing to bet that it was Widmore construction. My guess is that Widmore is a huge company that makes lots of different products.
- Kate's father was the Sergeant who asked Sayid to translate to find the U.S. pilot that Sayid's commanding officer knew about. (Ep: 2x14, One of Them)
- Kate's mother, Diane, served Sawyer in the restaurant. (Ep: 2x13, The Long Con)
- Hurley thought he knew Libby from somewhere and she said the flight, but we could find out something in future episodes about them running into each other previous to the flight. (Ep: 2x11, The Hunting Party)
- When Kate visits her father at the Army recruiting office, there is a picture of Sayid on the TV in the background. (Ep: 2x9, What Kate Did)
- Ana-Lucia pulls a gun on Travis (during a domestic disturbance)(Ep: 2x8, Collision). This is the same man who threatens to sue St. Sebastians after Jack's father operates on his wife and she dies (Ep: 1x11, All the Best Cowboys Have Daddy Issues).
- Hurley's lottery official (Ep: 1x18, Numbers and Ep: 2x4, Everybody Hates Hugo) is the anesthesiologist in one of Jack's surgeries (Ep: 1x11, All the Best Cowboys Have Daddy Issues).
- Hurley and his friend found a DriveShaft CD in the sale bin at a record store and tried to sing the lyrics to "You All Everybody", but couldn't remember the words. (Ep: 2x4, Everybody Hates Hugo)
- Jack and Desmond were both running in the same stadium and have a conversation (Ep: 2x23, Live Together, Die Alone).
- Sarah met Jack as he worked on her in the hospital after he decided to work on her instead of the man she hit with her SUV. The man, Shannon's father, died, and Jack ended up marrying Sarah. (Ep: 2x1, Man of Science, Man of Faith)
- The lawyers' office that Claire went to is the same one that Michael went to. (Ep: 1x10, Raised by Another) (Ep: 1x22, Born to Run)
- The priest who took Charlie's confession (Ep: 1x7, The Moth) later sold his scooter to Hurley in the airport just before Flight 815 departed (Ep: 1x24, Exodus Part 2.
- Charlie was in the crowded elevator at the Australian hotel when Hurley was late to catch his flight. Michael and Walt also stayed at the same hotel. (Ep: 1x24, Exodus Part 2)
- Anna and Jack meet each other in the airport bar before boarding Flight 815. (Ep: 1x23, Exodus Part 1)
- Sayid asked Shannon to watch his bag in the airport, but in a fight with Boone, Shannon told airport security that an Arab man had left his bag, and Sayid got in trouble. (Ep: 1x23, Exodus Part 1)
- The cars that hit Michael, Locke, and Kate (Kate ran into the car, which stopped her from driving away) look so much alike, that they are probably the same car. (Ep: 1x14, Special) (Ep: 1x19, Deus Ex Machina) (Ep: 1x22, Born to Run)
- Locke's mother was institutionalized at Santa Rosa Mental Health Institute, the same place where Hurley had visited Lenny. (Ep: 1x18, Numbers) (Ep: 1x19, Deus Ex Machina)
- Randy was Hurley's boss at the chicken restaurant and Locke's boss at the box company. After winning the lotto, Hurley invested in the box company where Locke worked. (Ep: 1x18, Numbers)
- Sawyer was in bed with Mary Jo, who is also the woman who read Hurley's winning lotto numbers on television. (Ep: 1x16, Outlaws) (Ep: 1x18, Numbers)