Silly question regarding manual tranny
 

Hello,

A coworker had a weird accident where he was driving his oldish Toyota
Sienna and tried to apply some engine brake with his automatic
transmission.

He was able to push the shaft up into Reverse; neddless to say, he
lost control and the car swerved hard and rolled over a few times. The
van was totalled, of course, but fortunately the driver walked away,
shakingly.

Now, the question is: is it possible to push the stick from the fifth
into reverse on my 2000 Civic manual tranny while having forward
movement? Or is there some mechanical stop that prevents me from doing
such a stupid thing? Not that I would ever want to do this, just for
my general knowledge regarding transmission design.

Thanks,

Serban