after taking the matches, they just reappear after "close mirror" and "open mirror"
the keyboard shortcuts for the commands are still the German ones
the door has no default action
you might also consider making Britney not clickable and use a Britney-inventory-item instead
did you change the speech font on purpose? it is hard to read

as reported, the game crashes after using the potion on Britney
the game also crashes after "use XXX with Britney" when you move the mouse cursor away from her while she talks