Use a power distribution block for your servos to prevent overdrawing current through the breadboard.
Add a testing state in the software so you can easily isolate and test the outputs of each sensor, event checkers, and state transition flow.
Modularize the mechanical assembly to allow for easy circuit debugging once the board is placed inside the housing.
Use an oscilloscope or multimeter to debug your circuit—what we thought was a software bug ended up being a fried 3.3V power rail! The voltage regulators on the breadboard power supply are a common point of failure.
Power all LED displays and buffer chips from the power supply unit, and not from the breadboard power supply.