Talk to the lawyer that submitted the petition.
If he/she feels that this is a 'material' mistake, he/she will know how to submit a correction.
PROFESSOR OF IMMIGRATION LAW for over 10 years -- This blog posting is offered for informational purposes only. It does not constitute an attorney-client relationship. Also, keep in mind that this is an INTERNET BLOG. You should not rely on anything you read here to make decisions which impact on your life. Meet with an attorney, via Skype, or in person, to obtain competent personal and professional guidance.
I recommend that you discuss this matter with your employer and suggest that they discuss this matter in detail with an immigration attorney. If a decision on your L1 case has not been issued, your employer can submit a corrected/amended L1 application. In many cases, the Premium Processing service can be very responsive and it would be a good idea to overnight a corrected original application as well as perhaps an email copy after contacting the Premium Process supervisor.
You should check with your employer and the lawyer who filed your petition. If the explanations are not satisfactory, seek out an immigration lawyer separately for a second opinion. There are many good immigration lawyers who answer questions here on Avvo.
If you appreciate the time spent preparing this answer, kindly consider marking it BEST ANSWER or HELPFUL. Also, please be sure to read my disclaimer below. Good luck to you.
Dean P. Murray
The Murray Law Firm
560 Sylvan Avenue
Englewood Cliffs, NJ 07632
Mr. Murray's response is NOT legal advice and does NOT create an attorney-client relationship. You should NOT rely on this response. Mr. Murray's response was generated without conducting a full inquiry as would occur during a face to face attorney-client consultation. It is likely that the response above may be made less accurate, or become entirely inaccurate, as you, i.e. the questioner, disclose additional facts that should only be discussed during a private consultation with an attorney. I strongly recommend that you consult an attorney who is licensed to practice law in your state (or, in the case of immigration law, and attorney in ANY state), whereupon all relevant facts will be discussed. All responses posted by Mr. Murray on Avvo.com are intended as general information for the education of the public, and not for any specific individual.