Great drama in the episode, but not understanding the massive crossbows utility. Earlier, they couldn't come close to hitting a dragon until it was nearly directly on top of them and even then, it barely sank into the dragon's shoulder. Now, they apparently have a range of 1/2 mile or more and are the most accurate thing ever invented and can blow a dragon's head off? Cersei's head of engineering deserves a raise.
Also, who's the traitor. No way for Euron to be waiting at Dragonstone unless someone informs them that Dany is on her way..... also she's a pretty terrible recon agent. She has dragons that can fly hundreds of feet in the air and allow her to see for miles, yet Euron still gets the drop on her? Terrible.