- Awesome Music:
- "Time to Kill" from "Brainzburgerz".
- "Tomboy Like You", "Get You Out of Here", "The Truth of It Is", "Victory's Mine at Last", "The Truth of It Is (Reprise)", and "Pigoilet" from "The Princess Most Fair".
- "Race to the Top", along with the other Top Gun inspired songs from "Where Dragons Dare". This is helped by the fact that Kenny Loggins himself is singing all of the songs.
- "It's Not Just Today" from the Series Finale, which plays over a montage of the residents of different dimensions going on with their lives.
- Crossover Ship: During a 2015 Comic Con panel, Sam Levine jokingly mentioned a Penn/Star Butterfly ship, calling it "Pennar Butterfly". Actual fanwork, however, usually depicts them as having a more sibling-like relationship instead. Fitting, as some consider PZ:PTH to be the "brother show" to SVTFOE and vice versa. It can be impossible for some to imagine one without the other.
- Ensemble Dark Horse:
- Matilda, the brown-haired background girl wearing a red hoodie and pink glasses, is slowly becoming this. Her most noticeable appearance is when she danced with Penn in "Lady Starblaster".
- Nearly all the show's guest characters netted a positive reception but Amber and Blaze were particularly well-received thanks to their prominent interactions with the heroes (it also helps that they're voiced by Olivia Holt and Sean Astin respectively).
- Starblaster, the galactic conqueror who Rippen harbored a crush on, deserves a special mention as well.
- The same goes for Orchid, the lounge singer from "Plantywood: City of Flora".
- Thanks to appearing in a studio photo, Maria began accumulating fanart before she even had a chance to make her official debut.
- Friendly Fandoms:
- With Star vs. the Forces of Evil, since both shows involve the heroes traveling to other dimensions. Fans even wonder what would happen if Penn and Star crossed paths. Interestingly enough, the crew members behind both shows are aware of this overlap and Sam Levine made a crossover joke during the show's joint panel with Star at SDCC 2015.
- A lot of viewers are also fans of Gravity Falls and Randy Cunningham: 9th Grade Ninja, two other Disney XD shows that faced similar network scheduling issues.
- Fans of Steven Universe also like the show, often adding or mixing together elements from both shows in fan works.
- Phineas and Ferb fans enjoy the show as well, even calling it a good Spiritual Successor for the former.
- He Really Can Act: A non-dramatic example; Thomas Middleditch (Penn's voice actor) and Larry Wilmore (Larry's voice actor) are pretty hilarious in "Rip-Penn", especially during the "pinwheel story" scene.
- Hilarious in Hindsight: Penn and Sashi's exchange in "Balls!" becomes this after the ending of "13 Big Problems".
- Ho Yay:
- Boone and Penn say "I love you" to each other in "That Purple Girl".
- When Boone thinks he's about to die in "3 Big Problems", he takes Penn's hand and announces his last request.Boone: If I don't make it, tell my best friend I love him.
Penn: I thought I was your best friend.
Boone: You are.
- In "Totally Into Your Body", Boone winks at his imaginary construct of Penn.
- Rippen and Larry hugging each other at the end of "Number 1, Number 2". Rippen doesn't even let go when they zap back to Phil mid-hug.Rippen: Yes, we're hugging, get over it.
- "Lady Starblaster" ends with Rippen and Larry dancing together while Rippen thanks Larry for always looking out for him.
- "Brainzburgerz" has Penn and Boone coming up with an elaborate skating routine together, which includes Boone lifting Penn into the air much like a ballerina.
- Idiosyncratic Ship Naming:
- Penashi = Penn/Sashi
- Petilda = Penn/Matilda
- Boonashi = Boone/Sashi
- Jerkass Woobie: Rippen's an unpleasant person, but when you learn his personal history and apply some thought to his situations, its hard to not pity him. Hes The Unfavorite in his family of villains, and hes often mocked and belittled by them (and his boss, Phil) because of his constant defeats at the hands of Penn (even if the defeat is the result of another villain interfering, e.g. Professor Evil Professor), because of Larry being Larry, or just for the heck of it. Hes only doing what he does because he wants to finally earn their respect.
- Memetic Mutation: Due to someone pointing out a typo on the iTunes close captions, fans have called the troll in the opening sequence "Charles".
- Nausea Fuel: In "Hail Larry", Penn revealed that Rippen threw-up six times during art class earlier that day. One can imagine what that looked like...
- Signature Scene: Penn restoring the Least Dangerous World Imaginable. ("My name... is Penn ZERO.")
- Squick: In "Number One, Number Two", Larry gives Rippen a "good luck gumdrop" he found in his shoe.
- Strangled by the Red String: Downplayed, but Penn and Sashi, while having some Ship Tease moments in the series, both showed more interest in other characters as romantic interests than each other. However, this is rather conveniently dealt with in the finale, as Pirate Maria casually tells Penn that it's not going to work out, Matilda hooks up with the class president (which itself counts as this trope, since she's (up to this point) only shown interest in Penn), and Blaze is dismissed as an option when Penn reminds Sashi that he's not human. It's possible that, if the creators had gotten more episodes, maybe even another season, then the pairing would have had more time to develop at a natural pace.
- They Wasted a Perfectly Good Plot:
- It's revealed relatively early in the series that for their jobs, the main trio replace people from the dimensions. While we do sometimes see the persons before they're replaced, and there are situations where they're replaced in the middle of something important, the aftermath of said event is never explored.
- Within the series, none of the alternate dimensions seen are shown to have an alternate counterpart to the heroes, or anybody for that matter. This issue is never brought up, and consequently, never explained.
- Ugly Cute: The Flurgle Burgle.
- Vindicated by History: An interesting example of this started happening not too long after the show had ended. When Penn Zero first aired, it wasn't necessarily deemed as being bad but virtually nobody had heard of it (Disney XD's erratic scheduling might've had something to do with this). However, the show has recently started gaining a lot more positive attention along with an increasingly growing cult following.
YMMV / Penn Zero: Part-Time Hero