Forest started the game well and Kasper Ankergren did well to stop Lansbury's goalbound effort as he managed to parry the ball away from the net.
© PA Photos
Leonardo Ulloa had a decent opportunity when a headed interception allowed him to break upfield but he could only fire wide.
Minutes later, Andrea Orlandi's free kick was well saved by Darlow and when Ulloa looked to follow up his effort was cleared off the line by Danny Collins.
From the resulting corner, Ulloa met Orlandi's cross and even though his header was saved he smashed the rebound into the net.
© PA Photos
Brighton were then indebted to Ankergren for keeping them in the lead as he made a great stop to deny Henderson from close range as he headed Andy Reid's pinpoint cross at goal.
Forest weren't to be denied their equaliser and McGugan finally broke through the Brighton defence when he smashed an effort in from a tight angle.
However, Gus Poyet's side regained the lead minutes later through Will Buckley as he latched onto Ulloa's pass and coolly slotted the ball past Darlow.
Billy Davies's side came back again to steal a point late on when Lansbury's effort went under Ankergren and into the net.