Mrs. Turner's parents are revealed in this episode.
This episode shows that Timmy gets his looks from his maternal grandfather (referencing how he takes more after his mom's side of the family than his dad's side of the family), as Timmy bares a strong resemblance to Vlad.
Ustinkistan fairies can only grant wishes involving turnips.
Even though Ustinkistan fairies can only grant wishes involving turnips, Cosmo and Wanda are able to poof up normal pajamas when it turns to nighttime, suggesting that Ustinkistan fairies can poof up something like nightwear even if it doesn't involve turnips.
Ustinkistan looks the same in the present and 50 years ago.
Timmy's grandparents are similar to Mama Cosma, Cosmo's mom, and Big Daddy, Wanda's dad, in that they don't like who their children married (Mama Cosma doesn't like Wanda, Big Daddy doesn't like Cosmo, and Mrs. Turner's parents don't like Mr. Turner).
Even though Big Daddy doesn't like that Cosmo's his son-in-law, he seems more willing to put up with him than Vlad and Gladys are willing to put up with their son-in-law and Mama Cosma's willing to put up with Wanda as her daughter-in-law.
Christmas and Thanksgiving - Two traditional Ustinkistan holidays mentioned were Yaksgiving and Yaksmas, which are references to the famous traditional holidays.
Ren & Stimpy - Yaksmas was previously referenced and celebrated in the short, A Scooter for Yaksmas.
If Timmy wished that his grandparents never came to America, then he shouldn't have been born, unless Timmy's own parents had met some other way without his grandparents coming to America.
After Timmy made the wish and changed its habitat, he wanted to go home. Wanda told him that fairies from Ustinkstan can only grand wishes that include turnips but when it gets dark (that lasts almost a year), Cosmo, Wanda and Poof put on their pajamas and they seem normal.
Mrs. Turner's parents giving their son-in-law sacks full of weasels (at the end they give him a sack of badgers).