Yeah that looks more like a train... for both the passenger compartment as well as the containers in which the drones are launching from.

To focus specifically on the drones... tactically that's probably the most sneakiest / concealed way to launch them. On a common vehicle (freight trains) that are constantly moving, thus making it harder to specifically track where they were launched from. If they happen to get close enough for the drones to be in striking distance, they launch. Even if the train is only within the strike range for less than 30-60s.

Non-moving places in which would be somewhat more exposed but still hard to track down would include container sorting yards, railway classification yards and even ports. Launching from container ships can work but much easier to trace because of the likeliness for sea-based radar to be in use, thus somewhat adding passive early warning.