Tutorial
I used an actual ghost town in Tasmania to make the background using google street view images. I put them together to make the background in a very long Gimp canvas (2560x360px). Left and Right ends must match.
I used ofn-scroll-layer script to make 2560 layers. Settings were Horizontal Step = 2, Tiles = 1.
Next exported all layers to a folder to reduce the frame number.
Then from a terminal:
Renumber layers after each of the above operations with the file manager.
This reduces frames down to 160 without dropping 2 layers in series.
The reason for all of this is the original image is over 30 gigabytes in size. This will hit the 'Gimp ram wall'. Unless you have a very powerful computer you will be unable to process an image of this size. So a lot of the image reduction takes place in the file manager.
Then 'open as layers' the 160 frames back into Gimp. Then I scaled them up to 1280x720 for video use. Making a gif just means scaling them down again to about 500px wide. I use an online GIF maker.
The 'rat rod' is a cut-out on a 1280x720 transparent background. To speed blur the wheels I used Gimp Circular Motion Blur and adjusted the angle till it looked right. Put this at the bottom of the layer stack and Filters>Animation>Overlay background.
Commands are for Linux modify for other OS's.