Kate Siegel's character from the last episode is credited as 'Leslie', but in this episode, Danny and her sister both refer to her as 'Joanna'.
Exactly halfway through the episode, everyone is gathered around the tech table at headquarters. The boom microphone, and then its shadow, can be seen in the dark gray area at the top of the screen while McGarrett says, "Endo is officially MIA. His phone is switched off. HPD has confirmed that he's not at home."
Adam keeps pronouncing Siobhan's name as Siovhan.