This very much depends on what you have studied as part of your undergraduate computer science degree. Generally, for the programming elements of the course fluency in the C++ programming language and any kind of 3D Graphics Programming in either openGL or preferably directX is useful.
For the mathematics elements of the course, the following are covered in the MSc course – Vectors (Vector geometry including dot and cross products), Applications of vectors (Geometry of the line and plane),Matrices (Matrix algebra), Applications of matrices (Homogeneous co-ordinates, representing planes as 4D vectors, co-ordinate transformations and perspective projections), Quaternions (Introduction to complex numbers and quaternions with applications to rotation and images), Ray Tracing (Introduction to ray tracing and an appreciation of its applications and limitations), Kinematics (Motion in a straight line under constant and variable acceleration. Mass and force. Newton’s laws of motion. Momentum and impulse), Collisions of bodies (One and two dimensional elastic and inelastic collisions. Work and energy), Projectiles (Motion of a body projected in two dimensions under the influence of gravity in the absence of air resistance, Motion in a horizontal and vertical circle (Motion of a body in both horizontal and vertical circles; motion on the outside/inside of a smooth sphere). It would be useful if you get some exposure to these things if your Mathematics is a little rusty – however we certainly wouldn’t expect you to do all of these things in preparation!