I just checked again, and it seems easy to replicate. Fail the first attempt, then after the first "No! It won't work!"-message, pick slower and just let the screams spawn. There won't be another message, the screams stop spawning, the music keeps playing and you can walk around still, but it doesn't progress. I'm guessing it's probably just a typo in a conditional check or something simple like that (I do that kinda thing all the time), but I figure if you can find it, you'll be more aware of it and be less likely to make the same kind of typo when putting together the full version.
I hear you about the multiple inputs for single actions thing... I sat around for ages just testing with my last game. I thought adding touch controls was going to be the biggest hassle, but it was actually allowing the player to unpause using the mouse without shooting as soon as the game starts again.
I think your games perfectly playable without using the mouse for dialog progression, just thought I'd mention it.