"Do you love mom and dad?"
Translation:Вы любите маму и папу?
Why does the accusative папа end in a у? Isn't it a masculine noun, and shouldn't change from nominative? Is this just a special case?
Because 'папа' ends with '-a' so it changes even if it's masculine. It always works like this, but most of masculine nouns don't end with '-a' so yes, we can say it's a bit special. The same with 'дедушка' (grandfather), 'юноша' (young man).
There are another special examples: 'дядя' (uncle) and 'герой' (hero) would be changed here too: вы любите дядю, вы любите героя.