I use this code to get a String array of headings used in a MS Word 2007 document (.docx):
dynamic arr = Document.GetCrossReferenceItems(WdReferenceType.wdRe
string[] is a vector - a 1-d, 0-based array. string[*], however, is a regular array that just happens to have one dimension. Basically, you are going to have to handle it as Array, and either copy the data out, or use the Array API rather than the string[] API.
This is the same as the difference between typeof(string).MakeArrayType() (the vector) and typeof(string).MakeArrayType(1) (a 1-d non-vector).