It is possible that the browser is running out of memory, the Gargantia model is quite big and the textures are not small either, the history mode also has tons of sound files. Could you give more details about your Android device? Do you know if your Android device supports compressed DXT pixel formats? If not, then the uncompressed textures would need decompressing, using even more memory.
I do agree that a WebGL demo should work on all OS, but to get the visual quality demanded by Production I.G. sometimes you need to sacrifice devices with not enough memory, but this was not done intentionally, as a browser game we do not have access to any information about the amount of memory we can use.
The demo should work on any browser, on any OS, we tested it on Mac OS X, Linux and Windows, and the visual result should be identical for all browsers Chrome, Firefox, Safari and IE11.