Hi there, no clue if anyone still reads this forum, but thought I'd post anyway.
I just watched the Console Any% WR and noticed you were looking at the gate itself to see if it was open, which lead to a missed timesave in one instance.
You can actually tell ahead of time if the gate will be open based on whether or not the white truck is in the car park.
This is the only environmental hint I specifically remember, but I vaguely remember there being others. Only just recently started playing this again after not having touched it since my childhood.
Hope this helps :)
So after playing some more, I've made a couple more discoveries.
At the start of the Alpine race, the exit to the main shortcut is blocked by a large mound of snow. On lap 2, a snow plow will appear nearby, along with 3 cones in front of the mound of snow. Normally, it will stay there for both laps 2 and 3, then clear the snow from the exit, opening the gate to the shortcut for use on lap 4. However, if you drive into the cones on lap 2, it will clear the snow earlier, allowing you to use the shortcut on laps 3 and 4.
In the Japan race, the main shortcut gate will randomly open on either lap 3 or 4. On the interactive track, between the starting line and the main shortcut gate, there is an extra basket which does not appear on the long track. If you drive into this basket on lap 1, the gate will open on lap 2 in addition to randomly opening on lap 3 or 4. As far as I can tell, this only works once per race and only if you hit it on lap 1.
Updated images for what was shared above:
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USA Shortcut (White truck)

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Alpine (Flag means gate is open)

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Alpine (Hit cones on Lap 2 to unlock shortcut for Lap 3 & 4)

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Japan (Hit basket on Lap 1 to unlock shortcut on Lap 2)










