What mistakes were made by Romeo and Juliet?

Answer 1

What makes you think they made mistakes, and what kind of a mean-spirited person are you to be focussing on them? To be sure, Romeo and Juliet had a sticky end, but that isn't necessarily because they made mistakes. And even if they did make mistakes, the play isn't about that. It's about their love, which, although they didn't live happily ever after because of it, they did live happily for a while at least, and for that short time, they lived more happily than anyone else in Verona or possibly the world. And that was no mistake.

Answer 2

When he visits her in the crypt, he notices colour in her cheeks, as if she were alive. He fails to come to the conclusion that she actually is alive.