Is the virginity test of Deuteronomy 22 an error, since the hymen can break without intercourse?

It is not an error, because nothing God does is in error. In normal life a woman's hymen does not break unless she does something very strenuous, like riding horses continually, which was not usual; so you judge by the normal behavior of women as the norm. In those days, women knew they would be judged on their virginity, so they took great care to protect it and avoided any activity that might put it at risk; when they rode horses they rode side-saddle precisely to minimize the danger. The law was severe on both sides: if the father produced the bloody cloth as evidence, the husband who had falsely accused her could never divorce her the rest of his days. So the law actually protects the woman, and society was not made of robots; a father could tell the elders that his daughter had to ride a horse all day and they would take that exception into account. What you really have in such a case is a husband who got cold feet and never loved the woman, and is falsely accusing her; he should not have married her if there was any doubt. Today women no longer protect their virginity, which shows how different this generation is, but in that culture it was a woman's most treasured possession because it assured her a husband.