Making sure your game runs on Internet Explorer 9 may require a bit more attention than any other browser.
IE9 Data File
In the Export2Canvas Settings window in the Compilation section you will have to turn on Generate IE9 Files. This will cause the E2C build pipeline to generate two versions of the data file. One version for regular browsers which is just a binary file and one version, which is specific for IE9. The IE9 version is Base 128 encoded (in other words, using 7 out of 8 bits in every byte). IE9 normally is not able to load binary files with XMLHttpRequest, however by reformatting it this way, IE9 now thinks it's a regular text file and loads it successfully.
Dynamic Color Change
This does not work on IE9 and IE9 lacks certain functionalities in it's 2D <canvas> rendering context which make it impossible for that functionality to be implemented in any feasible way.
WWW & UnityWebRequest Limitations
You won't be able to get any information regarding the response headers, because IE9 does not provide it.