While Orwell deliberately creates Mollie to be the most superficial of the characters, one that is almost laughable, there are some significant elements to her departure that Orwell is able to create to bring depth to something that could be mistaken as simply surface. Consider the opening in chapter 5, when it becomes evident that life on the farm and Mollie are not going to coexist well:
As winter drew on, Mollie became more and more troublesome. She was late for work every morning and excused herself by saying that she had overslept, and she complained of mysterious pains, although her appetite
was excellent. On every kind of pretext she would run away from work and go to the drinking pool, where she would stand foolishly gazing at her own reflection in the water.
In terms of her departure, Orwell constructs it as almost a foregone conclusion that Mollie would end up becoming a type of "slave" to the ribbons and sugar, along with the lavish attention that she so craves. When she does leave, Orwell's description brings out a level of depth to something so superficial:
For some weeks nothing was known of her whereabouts, then the pigeons reported that they had seen her on the other side of Willingdon... A fat red-faced man in check breeches and gaiters, who looked like a publican, was stroking her nose and feeding her with sugar. Her coat was newly clipped and she wore a scarlet ribbon round her forelock. She appeared to be enjoying herself, so the pigeons said. None of the animals ever mentioned Mollie again.
On one hand, there can be a clear indictment of Mollie in terms of her selfishness. Yet, the manner in which Orwell concludes the narrative of Mollie is extremely telling. The fact that Mollie is never "mentioned" reflects how Orwell believes there is a danger in the manner in which Animal Farm is constructed. The fact that Mollie can be "airbrushed" out of history, as if she never existed, is extremely telling. When Orwell makes it clear that Mollie "appeared to be enjoying herself," it is convenient and almost read as needed that she is removed from the memory of Animal Farm. In this, Orwell is suggesting that there is a fundamental danger in those who cross Animal Farm, or violate the rule of the pigs, in that they are not merely voices of dissent, but removed. There is a believe indicated that to stand against Animal Farm is not merely being oppositional, but rather assuming the role of an enemy that must be overcome and silenced. It is here where Mollie's departure gains significance. While it is "only Mollie," Orwell makes it clear that in her treatment and in her exclusion, the seeds are sown for how the other animals will be treated, and that those who oppose the farm suffer the fate of never being "mentioned again," like Mollie.