In Mark 15:40 it says that Mary was afar off beholding the crucifixion, but in John 19:25 says she stood at the cross.
We need consider that entire time of Jesus’ hanging on the cross was three hours, so it’s highly likely that both statements are true. This discrepancy can be easily understood by thinking about the vantage point of the witnesses. The women and John could have stood further away as the Romans actually performed the crucifixion, then drew closer to Jesus after He had been hanging on the cross a while. When the soldiers returned to break the legs of each, they would have withdrawn again. This is not only plausible, but reads quite naturally and would be what you would expect given the fear the Jews would have of the Romans at the time.