Why Scarecrow's Toxin Didn't Affect Gotham Earlier (Batman Begins Plot Hole?)

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Scarecrow and his enforcers were contaminating Gotham City’s water supply with fear toxin for weeks in Batman Begins, leading some viewers to wonder why it didn’t affect citizens before Crane and Ra’s al Ghul’s plans were enacted. The film provides a partial explanation, stating that the toxin is only effective when inhaled, but citizens were presumably vaporizing water in normal day-to-day activities for weeks, seemingly creating a plot hole. A line of dialogue from Scarecrow in act two, however, may explain why there weren’t widespread instances of Gotham citizens being poisoned before the League of Shadows initiated their master plan.

The Scarecrow, a.k.a. Dr. Jonathan Crane, was a corrupt psychiatrist who developed his signature fear toxin using a rare blue flower previously used by the League of Shadows. Crane intensified the flower’s panic-inducing effects and weaponized it, hiding dispensers of the toxin on his wrists. Working alongside the League of Shadows, Crane planned to unleash the toxin on Gotham, destroying the city by driving its population into a panic-induced frenzy.

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Scarecrow’s fear toxin was harmless in liquid form, only affecting people when inhaled as a gas. With this in mind, it seems odd that Batman Begins never mentioned Gotham citizens being poisoned by ordinary activities like showering or boiling water for food and beverages. Crane himself may have explained why Gotham wasn’t overcome with panic before Ra’s al Ghul enacted his scheme. After poisoning Rachel Dawes with his wrist-mounted fear toxin dispensers, Crane states that he gave her a concentrated dose, and he presumably gave Batman the same amount of poison during