He did a couple of good saves, i believe his best one was minutes before the second goal when he kept NF in the game. He also cleared the danger and collected the ball on several occasions to relieve his defense.
But, admittedly, his reaction in the first goal doesn't look good. Long distance and you can actually tell the player is going to shoot. As a keeper, the least you can do is get near the ball. Henderson wouldn't have caught that ball, even in the replay.
The second one is tricky. I was watching the game and i waited for the replays to see how that ball was directed toward the goal. It's OK to not anticipate a finish like that. On the other hand, it points to a specific thing that Henderson does. He often positions himself way ahead off his line for no apparent reason. Maybe, he thinks that he makes the shot/pass angle difficult for the attacker, but that usually works on certain occasions and if you have a big body type.
There were a few times, especially when Saint-Maximin was cutting inside or when Newcastle were finding decent shots just outside the box, that, if the ball had gone in, he would've conceded the goal standing. That's positioning straight from the Barthez school of goalkeeping.
It's early days, but Forest looked very unfit and unprepared for the PL. Oh, the scenes if they go down and the prodigal son has to come back to Carrington... We just can't do without drama at this club.