egladil opened the ticket and wrote:

When building or cloning a train, it can't be made longer than a certain length. However, when combining trains when dragging them in the depot window, only the length of the target train is checked. Neither the source train length or the combined train length is checked. Thus, by dragging the trains the right way, one can make trains many times longer than normally possible.
I can't say if the limit should be what it is now, or unlimited. Just that I think the limit should be the same everywhere.

An example on how to build a 700 wagon train can be found here: http://emil.djupfeldt.se/ottd/longtrain/

Reported version: trunk
Operating system: All

This issue was imported from FlySpray: https://bugs.openttd.org/task/36