Figured it out (I think...)! Just don't press 'E' on that stage. Basically, I implemented the dialogue system in a very silly way where a dialogue box is floating off in space, and when someone needs to say something, it zips off to where they are and populates the text based on who is speaking. I think when there are multiple people and only one copy of that text box, the game gets understandably mad because they all fighting over that one single text box object.