I know this is a little too late for this year but for next year!
Here are two of the things we used in our Amazing Race date. The first one was the T-shirts we made. The second was the flag placed on the doors for each task the guys had to do.
I am letting you download each of these for free if you want to. Just click on the picture and it will take you to where you can download the PDF version. Both are formatted to fit on an 8 1/2 by 11 inch paper.