Minecarts first appear on level 3551.
1. Connect next to the Minecart to move it along the track. They'll damage dots and tiles in their path. If a dot is weak enough, it'll roll over it and move forward.
2. Dots that take multiple hits can get in the way of Minecarts. Keep hitting Minecarts and they'll push through eventually!
3. Push each Minecart until it reaches its goal, the Reserve!