Mechanics
Mechanics, a name I've given to describe the domain of the mechanical engineer, is an extremely broad field that covers just about everything that isn't electricity or software; Mechanims, hydraulics, pneumatics, aerodynamics, combustion, refrigeration, even classical optics are all disciplines that fit well within the umbrella of mechanics.
A mechatronics engineer must be familiar with the basics of all of these areas; they provide a large pool of options for a design.
Physics
Mechanics is a branch of physics that helps engineers to design products that perform correctly and reliably.
Simple Machines
Simple machines are the elementary building blocks from which most real products and machines are made from.
Mechanical CAD Software (MCAD)
Mechanical CAD software (MCAD) is used in the design of almost every product manufactured today.
Robotics
Robots are complex electromechanical machines for automating tasks. They have immense potential (both for good and bad).
Manufacturing
Manufacturing, the science of making things, is also an art. Without manufacturing, we wouldn't have any of the modern conveniences we enjoy today.