Thanks. I called USCIS.

The woman was very rude. First she bombarded me with an nonemotional reading of some passage, to the effect that I need to send the card back and fill out I-50. When I ask about the time limit for us to do this, she immediately becomes impatient. What we are really concerned is that we may risk losing this card, or end up waiting for the correct card for a long time. I also said that the error did not seem to be a major one. She became even more impatient, saying any error needs to be corrected. I have seen such errors made based on this forum. Those USCIS officers are so careless, and do not respect other people's time and effort by making such careless mistakes, while they can not tolerate any single error in our mistakes.