No not the show. When I am making the slide show or editing a slide show to be able to change the order of the images. As the slide show shows them in order. One way is to have a sort order that can be put on each image.
in Slideshow UI dialogue, in General tab, right above the images table, there is a number of icons. The first two Icons from right to left allows you to change the position of the selected image (given that you already have images set in the Slideshow ).