I picked up the TPB of JLA Year One on my last trip back home and recently re-read it. Going through it again, I noticed something...odd. Nearing the end, when the aliens come for the JLA, GL and the rest switch places to trick the aliens. But we find out later that instead of switching costumes or the like, Hal used his power ring to change their appearances. The hell? Since when can a power ring do that? As Hal or any other GL ever done something like that before?
The GL ring creates the costume, and really, is only limited by the use's imagination, so don't think too much into it.
It's been awhile since I read any of the old Gardner Fox era JLA comics, but I know that the Justice League did stuff kind of like that on several occasions. JLA Year One had several moments of Mark Waid trying to recreate a Silver Age feel.