The Generation of Miracles all have names of colors in their surnames and hair colors. These colors are red, yellow, green, blue, and purple. The only color they're missing to make a rainbow is orange. There's one protagonist whose been distinctly compared to them over and over again. Now, what color is a Tiger? (Or should I say, Taiga.)
Following up on the above mentioned, why is Kagami's hair red over brown then? Brown is a composite colour that can be made with red, yellow, blue, green and purple. These are the colours of the rainbow, and as mentioned above, the Generation of Miracles represent one each. Akashi is also the one who truly gave Kuroko a fresh start to playing basketball and he represents red as well. In other words, Kagami's hair represents the fact that Kagami is Kuroko's fresh start over the Generation of Miracles.
His hair and eyes not being Colour-Coded for Your Convenience like the GOM probably also symbolises the fact Kagami is, as quoted from Aomine, "the Miracle who did not become one of the Miracles".
The numbers in episode 4 of season 3.
4 (death): to refer to the captain.
7 (luck): Midorima's shot never misses.
13 (unlucky): Haizaki's doomed to be ejected.
When you think about it, Kiyoshi's playing style was actually ahead of its time by a good 6-7 years. Kiyoshi's a center with the passing sense of a point guard thanks to his "right of postponement". Nowadays a big man who can play as a point center is highly coveted in the NBA. In many cases, this rare breed of players are nicknamed "unicorns". If Kiyoshi grew at least another few inches, he would be a player closer to Draymond Green's caliber. In fact, if he managed a full recovery on his knee, his career path would probably be similar to Green himself.