British citizen travelling from Mexico

Hi, this website is very useful, but just to check.
I'm a british citizen traveling from Mexico (MEX) to Manila (MNL) via Guangzhou (CAN).
Its actually, MEX - LAX - CAN(3Hrs) - MNL,
the return is MNL - CAN(3Hrs10) - YYZ - MEX

Just to clarify the information on this page, I would only need to apply for the 24 hour TWOV by filling in a landing card before I pass through?

Many thanks