Translation:Mom, look at that apartment with Dad.
its somekimd of a czech/slovak thing:
when you tell someone to do something with someone else together you use the 2nd person pl imperative and mentiom the other person like in this dentence.
i think its funny because now i understand why my mother (native czech-slovak) always says that word by word in german, which is wrong. but thats just how these languages work. :D
In practice, you can hear both singular and plural in these situations - it doesn't quite matter if you address the imperative to both of them or just the one you've mentioned in the vocative. Or even if you omit the vocative. But you're right that it doesn't quite match grammatically.
"Mum" is certainly not addressed formally here though. We stopped doing that about 100 years ago in Prague, 70 years ago in rural areas. Back in those days it was common to say "paňmámo" - a contraction of "paní mámo" (Mrs. Mum!) - it sounds ridiculous now :D -like calling your mother "mistress" in English.