the audio has case endings and is not representing " less- formal,spoken arabic"
It wouldn't be quite so bad if the case endings were at least the correct ones!
Yes, in this course most of the cases in the tasks are given wrong, especially when they attach the possessive pronouns - the cases given before them in this course are all wrong.
Best thing to do is report it as a bug to Duolingo here: https://support.duolingo.com/hc/en-us/requests/new. Unfortunately the course creators aren't able to fix this, but hopefully Duolingo can.