According to Inosanto, Bruce knew a Ba Gua form called 12 step, and possibly some more.
You wouldn't have any idea when he learned that would you? Before Bruce developed JKD I've heard it said that he felt he was somewhat limited as far as his footwork was concerned.
I just find this sort of interesting since I've noticed that Bruce's regular fighting stance is somewhat similiar to bagua with both feet turned almost at right angles to front and a little more than shoulder length apart. The weight also seems to be distributed 60/40.
Whether he directly took from bagua is up for speculation, but it seems possible since both Wing Chun and fencing normally only emphasize forward and backward movement while bagua's overall scheme is multidirectional.
The three components of combat are 1) Speed, 2) Guts and 3) Techniques. All three components must go hand in hand. One component cannot survive without the others." (WJM - June 14, 1974)