There is a glitch in the event "Aristocrat Leader's Hobby" where the last bit of dialogue spoken by Sir Turquoise has the incorrect voice over, and plays a voice over from a different event.

The Four Legendary Heroes are references to various influential people in the games industry:

Yuzusuki - Yu Suzuki (Sega).
Kuterogi - Ken Kutaragi (Sony).
Gheytz - Bill Gates (Microsoft).
Miamoto - Shigeru Miyamoto (Nintendo).

The Four CPU goddesses, and the lands they hail from in Gamindustri, are designed and named after consoles from the video game industry:

Neptune (Purple Heart) / Planeptune - The unreleased Sega Neptune. A two-in-one Sega Mega Drive and Sega 32X hybrid.

Noire (Black Heart) / Lastation - Sony's PlayStation 3. Her name is French for the color black.

Vert (Green Heart) / Leanbox - Microsoft's Xbox 360. Her name is French for the color green.

Blanc (White Heart) / Lowee - Nintendo Wii. Her name is French for the color white.

Compa and IF are named and designed after the game's developer Compile Heart and the publisher Idea Factory respectively. Both characters prominently feature design elements from the logo of their respective company (i.e. Compa's Purse, IF's Buckle).

Strangely, the DLC characters 5pb. and RED have no English voice clips outside of battle. If the game's voices are set to English, they will have no spoken dialogue at all in cutscenes, but if it is set to Japanese instead, their cutscenes are fully voiced.

According to series director Shingo Onodera and character designer Tsunako, Hyperdimension Neptunia's initial concept was a traditional fantasy JRPG that involved three princesses and a main character, reworked into Neptune (the protagonist) and the three other CPUs. The Martial Processor Unit in the first game was a leftover asset from this concept.