Robert of Gloucester was not captured at the Battle of Lincoln at the same time as King Stephen, as shown. Rather, it was Gloucester who took the king into custody. Gloucester's capture happened seven months later, in September 1141, at the Rout of Winchester.
The goof item below may give away important plot points.
Since none of Stephen's men returned to Lincoln Castle after the battle nor did anyone escape from it when Maud's forces stormed it (anyone who knew who Prior Philip and Jack were, at least), there was no way Richard could know for sure that Philip had been captured and especially not that Jack had been "killed", thus Richard could not have bring news about them to Kingsbridge.