Things that worked:
-MCP io expander was detected on i2c port.
-Motors worked as intended, motor driver was wired correctly.
-External headlights are worked correctly.
- IR distance sensor worked correctly.
-Buttons yet to be tested but were seen to be wired correctly.
-i2c display worked correctly.
Things that went wrong / improvements:
-J7 2x03 IO extender address selector had different pin numbering layout between the schematic and PCB editor.
-Silkscreen for j11 was upside down.
-Onboard LEDs D1-D5 were connected with a single resistor on the cathode pins. This means only 1 LED can light up at a time. Correct usage would have been an individual resistor for each LED.
-Silkscreen labelling was poor. Some reference numbers overlapped each other and the labelling of the pin header functions and the Arduino Mega pins would be helpfull.
-A multi-use power header would have been useful. Space for a small one in the bottom left corner is present.