How can Helly recognize herself in her first video message? Because she saw her own reflection in the stairwell door.
Cobel expresses the suspicion that Milchick ratted her out. There are in fact several compelling reasons for Milchick to do that:
Dylan threatened Milchick to tell Cobel about the ideographic card incident. Cobel usually doesn't mind Milchick's actions, and she herself was lenient toward interactions between departments, which lead to Dylan's stealing the card. But maybe Milchick still feared punishment from Cobel. If the new boss finds out about the ideographic card incident, Milchick can blame it on Cobel.
Cobel might send Milchick to continue the dangerous mission that got Graner killed, or she might continue the experiments that result in disarray (such as Dylan flipping out).
Helly appears to be calmer and more adjusted to life at Lumon before her suicide attempt, and there is even a flashback of her and Mark saying as much immediately before the act. In Real Life, it's not uncommon for severely depressed people to appear happier or more at peace once they've made up their minds to commit suicide (as they know they now have a way out), making the twist easier to see coming for those familiar with the subject.
The post-waffle part of the Waffle Party might seem like Mind Screw but is actually foreshadowed early on: as Word of God has mentioned, it's a sexual re-enactment of the "Taming of the Four Tempers," with each of the dancers wearing a mask representing a different one (Woe, Frolic, Dread, and Malice). The honoree is given a whip with the Nine Core Principles on it and meant to "tame" the Tempers just like Kier (presumably as a preamble to sex).
Fridge Horror
The Severance procedure seems like something that could easily attract people with mental health issues who find their lives intolerable. We learn this indeed is the case at least with Mark. Consider just how many others may have come to work for Lumon for similar reasons only to unknowingly consign their Innie selves into a bizarre hell.
