After the final try of their side's shock 28-14 win, a number of Tigers players appeared to taunt Bulldogs fans with the "khod" gesture, known as an equivalent to "flipping the bird" in the Arabic community.
Tigers players Samuela Fainu, Sunia Turuva, Brent Naden and Latu Fainu all made the hand gesture towards the southern grandstand, where a large contingent of Bulldogs fans were sitting.
On Sunday night, Tigers centre and former Bulldogs player Naden appeared in a since-deleted TikTok video in which he made the gesture and yelled "f***ing dogs" to the camera.
The video was reportedly sent by Naden to a friend and then leaked publicly.
The Bulldogs have a passionate Middle Eastern fan base and reached out to the NRL integrity unit, which is now investigating the matter.
It came after star Bulldogs signing Lachlan Galvin was verbally abused by a fan on-field before kick-off of Sunday's game.
Tigers members and fans formed a long guard of honour for their players on the field before kick-off, with the large crowd taking time to disperse.
AAP has been told that in the commotion, one fan stood only metres from former Tiger Galvin and yelled at the star, who controversially left the club to join the Bulldogs mid-season.
The Bulldogs are privately questioning why security was not on hand, particularly given tensions were always expected to run high with Galvin facing his old side for the first time.
Galvin was booed with every touch of the ball on Sunday afternoon, but coach Cameron Ciraldo said at full-time that the 20-year-old had taken the jeering in his stride.
"Nothing much flusters him. I thought he went out there, he did his job today. I don't think it rattled him that much. It's just we got beaten as a team," Ciraldo said.
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