An eyewitness tells ET that the family was all very supportive of Patrick at the event. "Arnold was in great spirits, chatting with others in the theater before the screening," the eyewitness says, adding that the former California governor seemed "proud" of his son.
As for Patrick, the up-and-coming actor was seen taking pictures with fans at the after-party, while Shriver and Christina mingled near the buffet. "Patrick was beaming. He seemed really happy to be there," the eyewitness reports.
Shriver took to Instagram on Tuesday to praise Patrick's performance.
"So proud of @patrickschwarzenegger and his work in The Long Road Home," she wrote. "Powerful. Moving. Must see TV. Patrick, you did an awesome job playing Sgt Ben Hayhurst. So proud of you to be in such an important project. Congrats to Martha Raddatz, Mike Medavoy and @natgeochannel. #longroadhome."
The Long Road Home premieres Tuesday, Nov. 7 at 9 pm. ET/PT on National Geographic.
Arnold opened up about his kids following in his footsteps while chatting with ET in 2015.
"[Patrick is] doing great," he said. "I'm so proud of him, but not only of my son. I'm really proud of my daughters and of my other kids. They are all really jewels. They're hard-working, and for me, the most important thing is that they are passionate in what they do."