The Sheep and the Workers (allegory)
The film opens with this very obvious allegory for the role that workers serve in society. The sheep, as they crowd into their pen, represent the workers crowding into the factory. The comparison is meant to suggest that the workers, and lower classes in general, have become docile servants of the upper classes, as well as convey the sense that they are being preyed upon in some way. Additionally, the allegory is important for calling to mind farming at the start of the film, an economy which Chaplin saw as superior in many ways to the industrializing economy and which afforded more freedom to the workers. In this new industrial world, it argues, the farmers, whose lives used to have some degree of control, have become the sheep.
The clock (symbol)
Behind the opening credits, a clock steadily advances toward 6 o’clock. On the surface, it is an expository device used to show that the work day is beginning before the film cuts to a shot of the workers entering the factory. However, it also serves a symbol for the march of technological progress that features prominently at the start of the film, as well as demonstrating the obsession with time and efficiency that plagues the society portrayed in the film.
Closed Circuit TV in the bathroom (symbol)
In the first few scenes, we see the President of the corporation appear on closed circuit television screens all over the factory. Then, while the Tramp is sneaking a cigarette break in the bathroom, we learn that the president even has a screen there as well, and can see into the bathroom. Though in this instance the Tramp is not actually using the toilet, one of the implications of the scene is that the president can even watch over the workers as they take care of private business, and determine whether they are moving fast enough for him or not. This technology did not exist during the Great Depression or when the film was made, but Chaplin uses this ‘futuristic’ technology to symbolise the omnipotent presence of the factory boss over every worker on the assembly line. It makes the workers paranoid that every little thing they do is being watched and could lead to losing their job if they do the wrong thing.
Misdirected bourgeois morality (motif)
Over and over again throughout the film, we are shown examples of the wealthy and powerful behaving in ways that they believe to be moral but which actually take advantage of or repress the less fortunate. The central driving conflict of the film—the dire costs of mechanization—is driven by this, in that many politicians and businessmen argued at the time that increased production would lower costs for consumers and help the lower classes. The child welfare officers are another great example of this problem, as they are tasked with the welfare of the Gamin and her sisters but their idea of taking care of them is similar to locking them up, and they treat the children coldly. Another notable example is when the wealthy woman tells the baker that the Gamin stole a loaf of bread, and then makes sure to tell the policeman to arrest her after the Tramp tries to take responsibility for the stolen bread. This scene uses a classic moral question—is it wrong to steal a loaf of bread to feed yourself or your family—in order to point out the problems with the woman’s behavior.
Shallow Water (symbol)
The Gamin finds a home for her and the Tramp while the Tramp is in prison, and shows it to him excitedly when he is released. It turns out to be more of a broken-down shack than a house, in an outskirt of the city, and keeps on falling apart in ways that physically harm the Tramp (beams fall and hit him on the head, walls and tables collapse under him, etc.). The morning after his first night there, he goes for a swim in the water near the house. Upon diving in head first, he discovers that it is only a couple of feet deep, and emerges rubbing the crown of his head. On a surface level, this is another example of the shortcomings of the house that the Gamin has found and demonstrates the difficulty and lack of luxury in which they live. Along these lines, the shallow water may symbolize that though they've found a home, there is still so much more that must be done in order for their dreams to be fulfilled. Further, it may represent the danger to workers and the lower classes that exists beneath the veneer of a productive, efficient society, or the illusion more generally that this society is functioning well, as Chaplin believed that the collapse of the economy was caused by problems with overproduction that lurked beneath the surface of an "efficient" industrial economy.