The bridge accident was an event that occurred on March 1st, 2009 in the matter universe. When James Zanasiu's away team attempted to travel through the Einstein-Rosen bridge, a member of the team named Lockdown panicked and used his psionic power to duplicate the bridge (and its occupants) into identical matter and anti-matter counterparts in the middle of the voyage.
The originals were spat back out of the bridge where they'd started. From their perspective, it was merely a failed jump.
The anti-matter bridge successfully made its trip to anti-matter Pelvanida, but a millenia too late. Several members of the anti-matter away team (James, Lockdown, Zachary, Siberys, and Shelton were spat out into anti-matter Pelvanida on February 31st, 3009.
The other away team members remained trapped in the bridge, with reversed coordinates. On James' order, Shelton reopened the bridge to the unknown coordinates and deposited the team on what turned out to be Gaman. (Card of Ten)