What are the essential items to include in a bicycle tool case for on-the-go repairs and maintenance?

Essential items to include in a bicycle tool case for on-the-go repairs and maintenance are a multi-tool with various wrench sizes, tire levers, a spare inner tube, a patch kit, a pump, a chain tool, and a set of allen keys. These tools will help you handle common issues like flat tires, loose bolts, and chain problems while out riding.