There were files in the games coding containing unused cutscenes where the confidants would get mad at the protagonist if he didn't visit them often enough. If he visited them after a long absence and answer the confidants' questions incorrectly, their relationship would be in doubt (as seen by an upside down tarot card) and he would lose the benefits of that social link until their relationship was repaired, similar to certain social links in Persona 3 and Persona 4. The reason this feature was removed is unknown.
Contributed by raidramon0
When Goro Akechi Spoiler:temporarily joins the Phantom Thieves in Sae Nijima's palace, he uses the persona Robin Hood, named after the famous outlaw of English folklore. When he Spoiler:confronts the Phantom Thieves in Masayoshi Shido's palace, they have to fight him twice. In the second fight, Akechi uses the persona Loki, based on the Norse god of mischief. This marks the first Persona game since Persona 2: Eternal Punishment where someone besides the main character can use more than one persona at a time.
Contributed by raidramon0
Almost all of the Phantom Thieves starting Personas are named after famous real or fictional outlaws or criminals.

• The protagonist's Persona is Arsene, named after the gentleman thief Arsene Lupin created by French author Maurice Leblanc.
• Ryuji's Persona is Captain Kidd, named after the Scottish pirate William Kidd.
• Ann's Persona is Carmen, named after the Gypsy Dancer seductress most notable in Bizet's opera.
• Morgana's Persona is Zorro, named after the famous Californian vigilante.
• Yusuke's Persona is Goemon, named after Goemon Ishikawa who lived during 16th century Japan.
• Makoto's Persona is Johanna, named after Pope Joan who disguised herself as a man to infiltrate the Roman Catholic clergy.
• Haru's Persona is Milady, named after Milady de Winter, the French spy from The Three Musketeers.

Futaba's Persona Necronomicon, however, isn't named after a person, but rather an object called a grimoire. This is a fictional magic textbook found in horror stories written by H.P. Lovecraft.
Contributed by raidramon0
Goro Akechi is a reference to the character Kogoro Akechi from the Private Detective Kogoro Akechi book series by Japanese mystery writer Edogawa Ranpo.
Contributed by DrakeVagabond
One of the early ideas was for Morgana to be a sports car, however, he would have been too small to fit the entire gang and so the idea was scrapped.
Contributed by DrakeVagabond
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A prototype image of the main character was drawn early in development. It was dropped after the artist, Shigenori Soejima, felt he had added too much and went for something simpler. Another early design of the main character was dropped due to Director Hashino claimed it looked "too professional". Soejima also commented that his initial changes to the design felt too cheap.
Contributed by DrakeVagabond
The protagonist's initial persona was going to be the German demon Mephistopheles. It was later changed to Arsene due to him fitting the theme of the game better.
Contributed by Zap Rotech
Director Katsura Hashino and character designer Shigenori Soejima revealed on the Persona Stalker Club V talk show that Confidant Hifumi Togo was planned to be an additional party member but was cut due to the story being too long at that point and not wanting to make it longer.
Contributed by Zap Rotech
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In the Korean and Chinese versions, Ryuji Sakamoto's civilian shoes had their "Rising Sun Flag" symbol removed.
Contributed by ProtoSnake
The protagonist's home in the game is Cafe LeBlanc which is a reference to Maurice Leblanc, author of the Arsene Lupin books which the protagonist's initial persona is based and named after.
Contributed by Zap Rotech
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In the subway station in Shibuya you can find ad posters that scroll to different ads. Here you can find ads for Rise Kujikawa from Persona 4 and Kanami Mashita from Persona 4 Dancing All Night. If you take a confidant to this location you will receive a Rise Poster that you can hang in your room.
Contributed by Zap Rotech
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When entering momentos for the first time, morgana reveals his ability to turn into a bus stating "For some reason "cats turning into buses" is an extremely widespread cognition among the general public." This is a reference to the Studio Ghibili film My Neighbor Totoro where the Main characters wait for a bus that turns out to be a cat.
Contributed by Zap Rotech
In order to Promote the game's release, The Los Cabos restaurant in Shibuya was officially fashioned in the theme of Persona 5 for a limited time.
Contributed by Zap Rotech
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The designs of the 22 Arcana are based on the Tarot de Marseille, a popular and influential Tarot deck from 16th century France.
Contributed by Kitsune Hawk
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During a scene in which the group is talking in Futaba's room, Yusuke will rearrange the poses of Futaba's sentai action figures into the poses of the Ginyu Force from Dragon Ball Z.
Contributed by Zap Rotech
When a new game is started in Persona 5, the player is prompted to accept that the game is a work of fiction. Refusing to accept this prompt will have the player told they're not allowed to play the game and being asked to leave, then returning to the title screen.
Contributed by KidDivinegon