When Peridot is lamenting her failure in capturing the corrupted gem, she looks at her hands with looks of sadness and anger.

She probably still misses her old limb-enhancers and doubts her own abilities without them. Homeworld taught her that she has nothing without them, and that the technological enhancements are everything there is to her. Even lying to her about her abilities.

She relies too much on technological extensions to herself and is trying to unlearn the idea that she has no worth without them.

That’s why she’s boasting and focusing on her own intellect throughout the whole episode. She focuses on her own mind as the source of her success, to prove herself that she’s more than just tech.

But when her brains fail to yield any results, she begins to doubt herself and her abilities, and the confidence and self-reliance that she worked so hard to teach herself.

That’s why this moment, as silly as it is, is so important.

It’s the moment she regained her confidence in herself. To prove to herself that she’s more than just technology, and she’s even more than just her intellect. She’s a person.