Shi ji lang

Or more precisely, the political propaganda making excuses for Mao's crime, which is his decision to launch the disastrous political movement of the Great Leap Forward which resulted in tens of million of people starved to death.

The movie itself, does not have much direct political propaganda that defends the Great Leap Forward movement directly, but, audience should not be fooled because such defense is done in an indirect way, i.e. the entire crew overcame the difficulties under the Party's leadership, which is no more obvious than the presence of the political commissar, a very realistic depiction in real life in China.

Hence, the implied message is that Chinese people unite behind the Party leadership to overcome the difficulties (which is created by Mao and his part first place).