This game has hidden developer credits.
Route-16 Turbo is a Japan-only enhanced version of the Route-16 arcade game.
At the title screen, press Up, Up, Up, Left, Left, Left, Down, Down, Down, Right, Right, Right, B, B, B, Start for some car-themed programmer credits scrolls from the top to the bottom of the screen. The names are likely references to the Toyota Corolla Twincam-16, the Honda CR-X and the Nissan Fairlady Z respectively.
Inaccessable Round 10
Normally, if the player collects all important items, the game will go to next round until they reach round 9. The player can never beat it because the developer set the number of items to collect higher than what can be collected.
Some rooms have a question item that needs to be changed into an important item if the player picks a correct yellow dot, need some guess and try. In round 4, it just tells you correct one by making it gray, and drops a weird white shadow... more oddly, that item is gray too, whereas it's usually red. The developer most likely set the wrong palette on it because the other rounds doesn't have this solution.
You can also control the demo. When demo go into room 086 and get that item, you can control it now! But it's demo, so if you crash, the game will return to title screen directly.