There was no ponies who made first debut in The One Where Pinkie Pie Knows, so instead I'm doing facts about Noteworthy:
* He is the first background pony to have only one voice actor in two different seasons (his voice actor is Brian Drummond in Seasons 1 and 4).
* He is the only pony whose first appearance was Winter Wrap Up who has only one voice actor in two different tones.
* In both The Cutie Map — Part 2 and Hard to Say Anything, he has green eyes instead of his usual amber eyes.

You can find more facts about him here

Next Saturday will be Cloudy Quartz and Marble Pie.