Pbj, Speeding Ticket, Road Is Incorrectly Labeled

I have a clean record and reside in Maryland. I got my first speeding ticket at 32 years old, 47 in a 30. i went to court today, plead not guilty, and had the officer point on a Google Map print out i brought of the intersection in question, close to where he lasered me. Turns out, when turning right at that intersection, there is no 30mph speed sign. in fact, a block after making that turn, the speed limit sign, the first one you encounter, says 50. it shows this on Google Road View as well. The cop pointed to me being in the 50mph zone actually.

The judge did not look anything up and still gave me PBJ, 11 months unsupervised probation. It looks like I cant appeal either. However, i do still believe i was wronged. Do i have any recourse? I will be reaching out to my dads friend who is a lawyer, but this is the first place i decided to post in the meantime.

Thank you!