"After breakfast, we went out."
Translation:Efter morgenmaden gik vi ud.
I agree that morgenmad would be more correct as morgenmaden is the breakfast vs just breakfast. :-) when en or et is at the back it is "the xxxxx". The car = bilen vs just bil etc. Just my view. :-) Therefor I also believe morgenmad should be acceptable as it is grammatical correct.
No. Danish, like all Scandinavian languages, has the V2 rule - meaning that the verb must always come second in the sentence. Usually the subject would come first - "Vi gik ud efter morgensmad", for example - but the other parts of the sentence may be shuffled to emphasise a specific aspect of the sentence, in this instance the time when the act was performed. When that happens - the verb must remain second, and the subject is pushed down the sentence. Thus - "efter morgensmad gik vi ud".