While browsing online, you could right click on the page with the missing image
with Internet Explorer, but as the image is not on the server I think it is
useless.
If the image shows online, then open Internet Explorer cache (the folder must
be located in C:\Documents and Settings\your_user_name\Local
Settings\Temporary Internet Files), then look for the missing files and copy
them in the mirror (remove [1] in the filenames)
Errors are common in most websites and unless the page is missing, your
browser ignores the errors by default.