A very successful film that takes a very simple situation— an saboteur commits acts of terror in London— and transforms it into a complicated and heartbreaking story. Upon googling the cast of the movie I came across a 2014 film also called Sabotage starring Arnold Schwarzenegger in what I can imagine is a bunch of tough guys in an action movie, judging from the poster. The Hitchcock version couldn't be further from an action movie, and more so the tragedy of a mother Mrs. Verloc (Sylvia Sidney) who is unaware of her husband's crimes. It's an artfully crafted piece with subtlety, where if you miss a shot you're almost immediately lost. Every moment has crucial information in it and like any good story each act builds on the information told in the previous.
What I would've called a Hitchcock gimmick back in The Skin Game now is a powerful moment: when Mrs. Verloc sees her son Stevie (Desmond Tester) in the crowd of children around her disappear and reappear. This was so successful because we know what Mrs. Verloc just went through, we know she's carrying the burden of a dead child, which let's us see things from her point of view. Alternately with Chloe's hallucination in The Skin Game, at that moment in the story we don't have enough information to know what her story is, therefore we can't empathize with her.
This story most excels as a moral take of the consequences of hiding information. Mr. Verloc (Oscar Homolka), fearful of being caught by the detective (John Loder) decides to give Stevie the bomb to deliver, which of course ends up killing him. It's horrific as we are following the boy, distracted as any boy is, unknowingly with a bomb in his arms the whole time.
Regarding the distractions, if you're a writer this is the best time to employ social commentary about things in life that are mundane. In this case it's the annoying street salesman who forces Stevie into the chair to try his B.S. hair products. Day to day, maybe not everyone would think a salesman like that is annoying, but under the lens of this dramatic situation it's juxtaposed so much with the salesman that it exposes how foolish he really is.
Other less important things to note: The aquarium scene made for a cool shot with the sea turtles in the background. The scene at the Simpsons restaurant with Stevie the Detective and Mrs. Verloc—when it cut to a two shot with out Stevie I just pictured him sitting there awkwardly. I thought it was cool aesthetic for the fruit stand man to be the Detective, maybe even better if they prolonged the mystery that he was a detective. So for awhile he's just this nosey guy who little do we know is trying to help out. Before the bomb explodes on the bus with Stevie, Hitchcock cuts quickly between different angles of the bomb for tension.
Lastly, when we find out the bomb was planted in the theatre I was trying to guess at what moment it will go off, and of course it happened at the perfect time —just after Mrs. Verloc says her husband is dead, which makes the film ending that much better.