
Continuity mistake: When Murdoch and Crabtree arrive to the fairground to apprehend Agnes, they lean their bikes against the "annual fair" banner stretched on a handrail. The camera shows the detective and the constable from behind, making visible that the weight of the bikes make the banner to ruck down significantly. However, when the next cut shows them frontwise, the banner is in neutral position. (00:40:30)
Answer: It's certainly a personal choice about using one, and probably similar to how some people refuse to wear a helmet or forego other safety equipment. Most bells and horns on bikes are not very loud and probably wouldn't be heard in busy traffic, making them mostly ineffective. Murdoch would likely still yell, even if he had a bell or horn.
raywest ★