As long as Muslims told you that it was time for prayer and you don’t have any reason to doubt that, it is correct.

I was in college, and I did not know when it was maghrib time.However the girls from college started to prayAlso, when I asked my friend she said that it is maghrib time. I also heard a guy praying on the other side, but I did not know if he was praying ‘Asr or Maghrib.Anyway, I prayed and i thought to myself, that i will go home and check whether or not I prayed at the right time, by checking the timetable for prayer on the internet. But i did not do this, as I forgot. Have I done something wrong?