As I watched The Last Recruit I noticed some parallels and ironies to previous episodes.
1. When Jack jumped off the boat and swam back to the island was similar to when Sawyer jumped out of the helicopter and swam back to the island in the s4 finale.
2. When Sawyer told Jack there was a pill for that (when Jack said he didn't feel right when he'd left the island before) called back Jack's drug addiction because he'd left the island and it haunted him.
3. When Team Sawyer emerged from the water was reminiscent to when the Oceanic 6 emerged from the water onto that random island.
4. Jin and Sun's reunion on the beach in front of the losties is similar to their S3 reunion on the beach in front of the Losties.
5. Sideways Jack looking at the mirror to see Locke's face is similar to when he performed surgery on Ben in S3 and looked at him using the mirror.
Can you think of anymore?