to error is human, unless .gov is involved, then it is unacceptable and possibly a felony.
And ignorance of the law is no excuse, but to NOT be ignorant of the law requires up to a decade in law school and to pass the bar exam.
There are undoubtably mistakes made all the time, and the vast majority will never cause any inconvenience at all, but the mountain of paperwork, the waiting periods, the background checks, and new for MD the waiver to allow police acess to medical records, not just criminal and public records, are not intended to stop crime, they are a deterrant for law abiding citizens to own firearms, give the government authority to deny your rights, and can even be used to generate a criminal record. Many people think there is going to be a battle royale in congress, leading to a firearms ban, confiscation, and mass non complyance in a giant show of pro 2A force, but in reality all they have to do is stop answering the phone at nics.