According to Jim Forester’s blog, Tony Jay was one of the people who auditioned for Happy Appy’s voice. “He was one of the better auditions,” said Jim, “but there was a problem. Jay's audition was too scary for kids. If we did put him in the show, we would’ve get phone calls from angry mothers on the very first episode. We wouldn't want that happening (although it did happen when Freddrick aired The Towers), so we declined it.”
Another audition for Happy Appy was Blair Meyes, who actually was originally chosen for the voice of Happy Appy. When they found out that Trestan did a better job of voicing Freddrick Gorgote’s idea for the character, Blair was removed as Happy’s voice.
Another notable audition was Jim Cummings as Happy Appy. He was declined because his audition sounded too much like Tony’s.
Despite the show being very low budget, a few big-name actors got to appear in parts of the show. Tress MacNiellie was the teacher in Happy Goes to School, Mark Hamill got to voice the lifeguard in Happy’s Vacation, and Tony Jay, despite being rejected for Happy Appy’s voice, used his Happy Appy audition voice to play the bullies during various episodes.
Jim Forester still owns some props from Happy Appy, the most notable being the beach jock apple that was going to be filmed in “Camp Aaah!”, various screenplays including The Towers, a miniature of Happy’s van, and the Bunsen burner from Happy Goes to School.
The whereabouts of the production reel shown to the Nickelodeon employees is unknown.
Happy Appy went through a total of four major design changes. The first two were made by Freddrick, and the last two by Tristan Drews.
The first design change was the one planned for “Attack of the Killer Apples”. It was noticeably different than Happy Appy. It had no stem, arms or legs, the eyes were all red, and it always had an evil frown but had no lips.
The second was the one shown on the production reel. The stem and limbs was added (but the stem didn’t have a leaf), the eyes were all white but had no pupils, and had a smile on his face.
The third was a very temporary short-lived replacement for the final design, which was lost behind the wardrobe of Tristan's bedroom. The closest to the final design, Happy’s third design omitted his legs, gave his white eyes pupils, and added his green lips.
The final design didn’t change much from the third design, only making his eyes blue and adding his leaf.
The synthesizer used for the Happy Appy theme is believed to be either a Yamaha DX7 or DX11.
The demo for the Happy Appy theme was recorded a day before the promo reel was shown to the Nickelodeon employees. It had John Tresti on synthesizer and Freddrick on vocals, as they couldn’t find the right kids to sing the lyrics. A few days after the show was approved, the theme was recorded again in two tracks; synthesizer and vocals.
The intro of the show was done a day after the theme was recorded, and took six takes before the crew got the intro right.
When Freddrick Gorgote 'died' of suicide, the Happy Appy Tsunami hotline was disconnected.
Trestan Yae was sick when Hurt Happy and “The Happy Dance” commercial were made.
The person who voiced Happy Appy in Season 2 is debatable, but the most likely two options are Freddrick and Lloyd Meyers, a man who was a friend of Freddrick Gorgote when Freddrick had become insane. Since Lloyd Meyers is voicing Happy in Season 3, it is safe to say that he did Happy's voice in Season 2.