The railway pass where they hide the empty methylamine barrels for the heist appeared also on the 2008 movie Appaloosa, when the train is stopped and the main characters aim at Renee Zellweger captors.
When Hank asks Walt if Skyler is going to therapy, he answers that she's going with a man named Peter, though he couldn't remember his last name. At the same time, on the credits, the name of Peter Gould, co-executive producer of the episode, appears.
The trivia items below may give away important plot points.
Hank asks Walter Jr. if he wants to watch the movie "Heat". "Heat" is a film about men pulling off a heist, but miss one factor that could potentially lead to them getting caught. Walter and Jesse do the same thing with their train heist, the killing of the kid on the bike being the one factor missed.
On the opening scene with the young boy on the dirt bike, after he has put the spider in the glass bottle, you can faintly hear a train's horn in the distance. This is the train that Walt, Jesse and Todd steal Methylamine from.
After Todd has shot dead the young witness on the dirt bike, the camera lingers on the bottle containing a captive spider dropped by the murdered boy. The image of a spider in a bottle is metaphorically used by Queen Margaret in Shakespeare's tragic play to describe the scheming and ruthlessly homicidal Gloucester (who later becomes the titular Richard III). It is an equally apt metaphor for Walter White's thoroughly malevolent character. "Why strew'st thou sugar on that bottled spider / Whose deadly web ensnareth thee about?"