As stated in the title some keys don't work when trying to input my password into the Yosemite login screen. The weird thing is that if my mouse isn't plugged in (Razer Naga) when I turn on my Macbook Pro the issue doesn't occur and if I restart my Macbook Pro, even with the mouse plugged in, then everything works as expected. Anytime the Mac is restarted in the keyboard works as expected on the login screen but when powering the Mac on it doesn't.
I have done an SMC reset to no avail. I never had this problem in any previous versions of OS X.
UPDATE: I started plugging my Razer mouse into a monitor stand with a built-in USB hub and now the problem almost never happens... it still does occur, but probably only 10-20% of the time as opposed to 100% when the mouse was plugged in directly to the Macbook on startup.