The first costume that Goku wears in the series is a significant milestone in the history of Dragon Ball. This iconic outfit features an orange gi with a blue undershirt, a blue belt, and blue boots.
For many years, people believed that the orange color of Goku’s outfit (as well as Krillin and Yamcha’s) was a mistake in the anime Dragon Ball.
However, those who claim this, although incorrect, have consistently defended their stance. It is said that there are two colors: one for the anime and one for the manga.
Over the years, it has become evident that the animated adaptation transitioned to the orange color, and the initial episodes were predominantly colored this way during the late 80s and early 90s. Toei Animation notably altered the color palette, depending on changes in animation quality.
Interestingly, Goku’s outfit and the Turtle School’s uniforms are orange, and according to Akira Toriyama, there is a reason for this choice.

Goku’s Orange Outfit in Dragon Ball
According to what Akira Toriyama revealed in an interview, Goku’s outfit is orange because it is inspired by the clothing of the Shaolin monks, although it is commonly depicted in a different color.
The color orange is a vibrant hue that conveys various meanings across different cultures. This color is quite prominent in Asian religious traditions, with many monks and religious figures donning orange robes.
As has been noted, the author Akira Toriyama drew considerable inspiration from martial arts and Chinese culture to design the storyline of Dragon Ball.

In Japanese and Chinese culture, the color orange represents enthusiasm, determination, happiness, love, and good fortune. These attributes align perfectly with Goku’s character and Master Roshi’s principles in martial arts.
In summary, Goku’s orange costume symbolizes strength, determination, and the spirit of the character.