Lights, camera, faction. Actress Gabrielle Union fired off a lawsuit against BET, claiming the network tried to short-change her by stuffing more episodes into a single season of her show “Being Mary Jane” than she agreed upon, according to The Hollywood Reporter. The 42-year-old star contends producers for the hit series vowed that seasons would never run more than 13 episodes, but they’re now trying to jam 20 shows into Season 4. Union is slated for a raise from $150,000 per episode to $165,000 in Season 5 and believes the network is attempting to “fraudulently extend” the terms of her contract, according to the lawsuit. The contract she signed, however,…