This is the 100th episode of the series.
In 2013 on the night of the Particle Accelerator explosion, the way Harrison Wells (Eobard Thawne) extends his flat out hand, to shake hands with Cisco, is similar to the erased timeline in S1, Out of Time (2015), when Eobard reveals his true identity to Cisco before killing him by phasing his hand through his chest.
Tony Todd reprises his voice as Zoom; coincidentally this episode was released on Todd's 64th birthday.
The episode's title is a reference to an infamous line from the William Shakespeare play The Tempest.
At one point, Gideon was about to say that Nora is the fifth recruit of the Legion of something, before Barry interrupted her. This is a reference to the Subject episode The Trap (2015), when Gideon was about to say that Barry is the founder of something before he interrupted her.