Nice fun song. Appropriate title :)
-Critiques-
Drums were repetitive. I assume you were experimenting but I think you should polish your songs before uploading to NG. So add more variety to the drum riffs (breakdowns, variations to drum riffs)
I see you many several melodies in this song. All you really need to do is take one melody and make variations of it and play them at different parts of the song. You can add a second melody but that's pretty much all you really need.
-Good Stuff-
This song just sounds nice.
The drums WERE plain but you CAN use those to make awesome drum riffs. Good selection tbh, it has a lot of potential. I think you should reuse them in another song using my critiques above.
3.5/5
Keep working hard :) and to answer your question, yes a G major scale with the root D is D mixolydian. From D to C in the key of Gmajor, going up, is whole-whole-half-whole-whole-half.
If you have any questions you can PM me.