The best translation would be "run out of the park." The Duo team are fixing these, but haven't gotten to all of them yet, I guess.
I guess it is good enough for English, that language not being so nitpicky about these nuances.
So many translations are not accepted in this course :-( and often I am not sure, whether my English is so bad, or it is just the programm.
In English, 'run out' of the park is a simple description of what the dogs are doing. In contrast, 'run away' adds the idea that the dogs are deliberately trying to get away from the park.
Egy másik feladatban, ugyanebben a leckében (a több választási lehetőségnél) out from-mal van. Itt is el kellene fogadni vagy ott kellene out of-ra javítani!