Multiple Suns
One of the most classic characteristics of a sci-fi movie is multiple suns. This was made famous by George Lucas when he gave Tatooine two suns. Since then, multiple suns have appeared in every sci-fi movie, including GOTG. James Gunn found a pretty neat way to pay homage to this sci-fi trope by giving the planet Xandar three suns.
To solidify the point that Xandar has multiple stars, the Nova Corps’ army has a tri-sun emblem on their chest. So, there’s definitely no way of mistaking where the Nova Corps comes from. This tiny detail shows how detail-oriented the production staff was.