Use the pull from front wagon extension and place this wagon behind the crafter so rails can automatically be launched to the flag after being crafted.
Use the magnet extension to transport nearby items to the flag for you. This includes tools so you do not accidentally lose them. Combine the magnet with the autodrop extension and the dynamite and torpedos can automatically be launched
Place the flag at the end of the map and throw resources (especially rails with the pull front extension) in a pile to the end.
If you place the flag on the furthermost rail the railroad will build itself in one direction. If you want to change directions you need to move the flag. Use this on the Lava boss to build tracks quickly.