Nine points from the boot of Dan Biggar looked to have won it for the home side until Jones' 78th-minute effort bagged the Scarlets a share of the spoils.
And while Rees - who re-iterated his desire to be back in the Wales squad for their friendly against Australia next month - was pleased to be back in action it was a case of mixed emotions post match.
"The neck is fine," said Rees - who missed the World Cup with a neck injury and has not played for his country since the RBS 6 Nations defeat in France in March. "My shoulder was a bit sore but it was just nice to be back playing really and I am looking forward to playing again next week.
"The result was disappointing really. We missed some kicks at goal which would have won it for us. We spoke about what a big game it was for the pack all week and the scrum went well for us.
"I am only 30 and still have a lot I want to achieve in the game and this injury I have had has probably added a couple more year to my career.
"I still want to captain Wales, there is another Lions tour and another World Cup and I want to win things with the Scarlets."
Despite being held to a draw the Ospreys remain at the top of the table on points difference ahead of Leinster, who avenged last season's Grand Final defeat by beating Munster 24-19.
Ireland fly-half Jonathan Sexton was the star of the show kicking 19 points on a weekend dominated by the boot.
20-year-old Glasgow fly-half Duncan Weir did his chances of a Scotland call-up no harm at all with all 18 points as the Warriors beat Aironi 18-6.
And Edinburgh rookie No. 10 was not far behind Weir with 17 points as the Gunners also emerged from a trip to Italy unscathed, beating Treviso 22-11.
With Friday night's clash between Newport Gwent Dragons and Cardiff Blues postponed due to a waterlogged pitch the only other game of the weekend was Ulster's comfortable 22-3 win over Connacht.
Ireland hooked Rory Best was the man-of-the-match but it was fly-half Ian Humpreys'12 points - including a late try - that did the damage.