I believe the flickering is to tell you that one of your items has hit an opponent, which makes sense with the use of bananas you mentioned. There was something similar in the original (at the very least, your player would yell in triumph).
And indeed the flickering also happens when someone uses the Start item, which makes all opponents smaller, slower and more vulnerable.
No it does not start to spin, the car just pass throught it like if it isn’t there. I will try in a different machine/os/browser.
Do the opponents obtain items?
Cool stuff. 
Very impressive!
Simply epic. That was one of my favourite maps back then. Just one thing: Are the green shells target-following?
Green shells fire directly forward of the player. Red shells home in on the opponent whose rank is one higher than the player. And, blue shells navigate along the track until it homes in on the player who is currently in first, potentially hitting other players along the way.
In the original game, green shells traveled in straight lines, bouncing off of walls as it progressed through the track. Due to byte constraints, I simplified the motion. The green shells still fire directly forward, but they will also follow the curves of the track instead of bouncing around them. You can actually take advantage of that to target other players.
And, by the way, it really is the map from MK64 except for the elevations; this version is more hilly.
Quite interesting. I wish I knew how to do spectacular 3D in 2D 
Good job on this!
I just posted a new version.
In the prior version, when you applied the star, you became temporarily invulnerable and the player flickered until the star was used up. However, in the new version, the player cycles through different colors instead.
Also, thunderbolts temporarily shrink all the other racers making them slower and weaker. The background flashes when a thunderbolt is applied.
In the new version, the player can obtain either 1, 3 or 10 mushrooms, the latter taking place of the golden mushroom due to space limitations.
Triple red shells work, but the green ones disappeared the first time I hit C. I first thought you gave items to any carts that passed a line of item boxes because I seemed to get them even when I obviously missed. Later the opposite occurred. ???
Have you seen the download stats on java4k.com? You’ve got 2000 more views in the last 24 hours. I wonder if you’ve been slash dotted or something. Excellent game by the way.
Probably a result of this post:
http://www.ign.com/boards/threads/demake-of-rainbow-road-mk64-thats-only-4096-bytes.452902945/
Hey zeroone trying to compile the source code provided in java4k.com site but getting this at run time:
Exception in thread “Thread-1” java.lang.ArrayIndexOutOfBoundsException: 707
at a.run(a.java:244)
at java.lang.Thread.run(Thread.java:662)
The java4k.com page appears to be stripping out backslashes. You can find a zip of the source at this mirror: