As the family moves to a new safe house, Sarah and John separate from Derek and Cameron. Sarah takes John to Charley Dixon's new home. Derek and Cameron are attacked by mysterious human heavies. A power outage shorts out John Henry, compromising his programming. Cameron reveals a secret about Jesse. Sarah finds a lump, but it's not what it seems.
- Arc Symbol: We finally see that Sarah's "three dots" belong to The Turk.
- And I Must Scream: When John Henry is powered down, it seems an eternity of slow death to his fast-processing mind.
- Bread, Eggs, Breaded Eggs: "On a scale of one to ten, one being a hangnail, ten being Hurricane Katrina, this is Katrina with a hangnail."
- Bucket Boobytrap : Of a sort. When Cameron walks into the warehouse to rescue Derek, she's soaked.
- Cain and Abel: John Henry identifies the hostile AI as his "brother".
- Continuity Nod: When Derek and Cameron are clearing out the storage locker, he tells her off for removing some of his plastic explosive, and she refuses to tell him what it was for. It's probably for the explosive charge she put into her head three episodes previously so that John could kill her if it ever became necessary.
- Evil-Detecting Dog: Too late, unfortunately.
- Foreshadowing : The bottles of water in the warehouse are a hint of the next episode.
- Heroic Sacrifice: Charley appears to die holding off Skynet's minions so John can escape.
- Mood Whiplash: The episode starts as if it's going to be a quiet character-driven episode in which the central cast deal with the emotionally wrenching events of the previous three. It ends up featuring a certain Big Name franchise villain making a shocking debut in this continuity and trying to wipe out most of the regular and recurring cast, and the violent death of a major sympathetic recurring character.
- Sacrificial Lamb: Poor, poor Charley Dixon, who dies trying to protect John.
- Shout-Out: The title is a reference to To the Lighthouse by Virginia Woolf. In addition to taking place at a lighthouse, the episode, like the novel, deals with themes of death, separation, and family.
- Tracking Chip: Sarah's breast lump turns out to be a homing device implanted in her body while she was captured by Ed Winston.
- Wham Episode: Skynet is already active.