Leaving the door open is a common enough saying and using the plural here is a way of grounding the saying in a more real sense, i.e. going back to the metaphor itself instead of staying with the generic phrase, and apparently this metaphoric house has more than one door.
This is by no means an error, it is a deviation from the expectation to emphasize the carelessness of the person leaving multiple doors open.
Ich beisse; wo ist der Fehler?
Wiktionary
Leaving the door open is a common enough saying and using the plural here is a way of grounding the saying in a more real sense, i.e. going back to the metaphor itself instead of staying with the generic phrase, and apparently this metaphoric house has more than one door.
This is by no means an error, it is a deviation from the expectation to emphasize the carelessness of the person leaving multiple doors open.