A number of years ago I just walked up to the theater and asked for a playbill and the house staff was kind enough to give me one. Not sure if that’s still the etiquette today, but it’s worth a try. Also trying to just slip into the theater as the show is being let out (dressed and acting like you just saw the show and you’re simply going back into the theater to retrieve something) and pick up a playbill. If security tries to stop you, just explain that you’re getting a playbill.
I’ve also heard that Joshua does in fact sign and take pictures.
"Mostly, I loved the size of these people's emotions. Nobody has emotions this size anymore. Outsized emotions. Operatic emotions. Kushemski and Vanda are like Tristan and Isolde, they're Paolo and Francesca. Nobody's in total thrall like this anymore. Nobody's overcome by passion like this, or goes through this kind of rage." Thomas, Venus in Fur