Penny Polendina alludes to Pinocchio. This allusion has had the following influences on the character and story:
- The name "Penny" is similar to "Pinocchio". Her last name, Polendina, comes from the derogatory nickname that Pinocchio's creator, Geppetto, was given, due to his yellow wig bearing resemblance to polenta in the original story.
- She is a sentient robot. Pinocchio is a sentient wooden puppet.
- In "A Minor Hiccup", Penny says "I'm not a real girl." This statement is similar to Pinocchio's statements of wanting to be "a real boy".
- In the same episode, Penny hiccups whenever she tells a lie, just as Pinocchio's nose would grow in length whenever he told a lie.
- She manipulates her swords through the use of very thin wires, similar to how a puppet is controlled with thin strings.
- Penny receiving the power of the Winter Maiden from Fria is an allusion to her finally becoming a real girl due to the power only being able to bond with Aura, similar to Pinocchio becoming a real boy upon receiving the Blue Fairy's blue magic.
There are a few small differences in appearance between the show and available concept art versions of Penny from Volumes 1-3, such as the lack of exposed shoulders and the lack of frills on her thigh highs as well as neck wear. One piece of concept art shows that she almost had a pouch strapped to her lower back. There are no such differences between concept art and show appearance with Penny's Volume 7 design.