History Recap / OnceUponATimeS4E5BreakingGlass

* AbsenteeActor: Mr Gold, Henry, and the King and Queen of Arendelle did not appear in this episode, despite their actors' names in the credit.
* BerserkButton: Sidney pushes Regina's when he betrays her. She is, justifiably, incredibly pissed... and that's putting it ''lightly''.

* RomanticTwoGirlFriendship: Emma and Lily's, shown in flashback. Fans have interpreted it as [[HideYourLesbians something more]], at least on Lily's side.

* MythologyGag: Calling back the original events of ''Disney/{{Frozen}}'', Elsa recreates her ice bridge from "Let It Go" to cross a gorge, using the exact same hand motions and posture when running. Also, after the Snow Queen traps Elsa in her fear-manacles and Elsa demands what she's going to do, she replies, "I'm going to build a snowman."

** Also, she is assembling a MagicMirror to somehow help her get the family and love she feels has been denied her, and for this she needs a piece of Sidney's mirror (because it was imbued with dark magic by Regina).

** Regina also invokes this when confronting Emma about having brought Marian back (crossed with a dose of ThisIsReality) in that, even though she didn't mean to, it happened and it hurt her...so that not only will she never forgive her, that's just the way life is--bad things happen which can't be undone so you just have to "learn to live with it". Subverted a bit when Emma reveals she didn't want her forgiveness, just to still be her friend, and the gesture touches Regina enough to let her walls down a bit.

Regina reluctantly teams up with Emma to search for the Snow Queen after Sidney, who is once again Regina's prisoner in the mirror, discovers her whereabouts and agrees to lead her to the location. With Belle babysitting baby Neal, a nervous Mary Margaret and David prepare for their first date night away from their child and find themselves on a mission to track down Will Scarlet, who has escaped from the town jail, and Elsa sees Anna in the Storybrooke woods. Meanwhile, back in the past, young Emma finds herself a kindred spirit when she befriends a girl who, like her, is a runaway orphan.

* TheReveal: The Snow Queen was Emma's foster mother.
* RomanticTwoGirlFriendship: Emma and Lily's, shown in flashback. Fans have interpreted as [[HideYourLesbians something more]], at least on Lily's side.

* WrongGenreSavvy: Mary Margaret is convinced that her husband David has released Will (as part of a plan to give Snow a short break from watching over their newborn son) and absolves him of the crime in exchange for his admission. But Will really had escaped.

** Lily mentions wanting to be special like HarryPotter.

!Tropes

** The episode's title could be considered a big one considering that the actor who plays Sidney Glass was formerly on another show all about [[BreakingBad 'breaking things' and a different kind of 'glass']] entirely.

* IdiotBall: Regina really shouldn't have threatened to put Sidney back in the asylum.