Yeah there are a lot of broken game mechanics at the moment. For example, you can queue up a ton of units to "store" population, let city population grow, store away more population as units, etc - then once you have enough units queued up, cancel all the unit training at once, which will return the population to the city, letting you hit population cap with no need for farms or agriculture. It's a placeholder system, the "real" economy will be implemented in a later beta build.