By default, the eXtyles XML export process will warn if it encounters any images (including drawing objects as well as pictures) in the Word file. It will also include a warning <!-- INSERT PICT --> in the XML at the point that the image was encountered.
If you were not expecting the file to contain images, you should always examine the cause of this warning. It may indicate that an object that you thought was a MathType equation was actually a Word picture, for example. It may also indicate that the Word file contains drawing objects (such as text boxes, arrows, etc.), which will not form part of the XML, that you thought were part of the exported Word document structure.
Sometimes, it is not clear from the position of the <!-- INSERT PICT --> warning in the XML exactly where the image is in the Word file. Try viewing the Word file in different views - while pictures are not visible by default in Draft view, you may be able to spot the small black square “image anchor” to the left of the paragraph where the images is located - if you then switch to Print Layout, you should be able to spot the drawing object.