To "skip" is to leave one's known place of residence in order to avoid responsibility for a debt or criminal act. Similar to bounty hunters, skip tracers are employed by a wider range of entities including debt collectors, repossession agencies, attorneys, private investigators, bail bond agencies, and process servers to locate the individual who skipped.
Main Plot Points
Person of Interest: Francesca (Frankie) Wells, a skip tracer searching for Ray Pratt, a small-time criminal who murdered her brother.
Later in the episode Beth Bridges, the mathematician developing a predictive algorithm designed for Samaritan, becomes a second person of interest when Root pursues her in order to protect Finch.
Reese learns that the Machine has made contact with Harper through encrypted texts sent by its human alias Ernest Thornhill.
Beth Bridges is developing a predictive algorithm, an analysis tool designed to calculate the likelihood something will, or will not, happen. Such predictive analyses are used in a wide variety of applications, from college admission decisions (based on test scores, grades and other measures) to credit decisions, to sales and marketing, where such models predict what products a consumer will buy based on past purchases.
Chloryl-hydrate is a mild sedative; when mixed with ethanol, it forms a compound euphemistically known as "knock-out drops."
Writer Ashley Gabletweeted a picture of the whiteboard from which she built the episode outline. Gable noted that the plan was originally to have Zoe appear in the episode rather than Harper, thus the question CAN WE SAVE ZOE? at the end of the final act. The board also notes that Root has control of the Trojan Horse trigger, which was not seen in the actual broadcast.
Bloopers and Continuity Errors
Frankie refers to Reese (as Reilly) as "Crockett", a reference to Miami Vice detective Sonny Crockett.
"It was a brilliant plan Harold, the Trojan Horse, but it would've gotten professor Whistler killed." (Root, to Harold)