In a scene at Mattie's school, in Washington, DC, one school bus in the background is clearly a Crown product; however, Crown coaches are almost entirely limited to the Far West, and they are extremely rare anywhere on the East Coast.
When Merideth's friend says there should be a certificate number on the diamond and he doesn't see it. It would be believeable if he didn't use a magnifying glass which is 4 magnification and to see the number you need at least 30 magnification