Getzlaf matched Selanne with a third period assist, the 709th of his career. Getzlaf also holds the all-time club records in games played (1,110), assists and power-play assists (246).
"That's one of the coolest things I've been a part of," Trevor Zegras said. "What he brings to this team is more than any one person. To just be a small piece of his unbelievable career is something I'll remember for the rest of my life."
John Gibson made 38 saves in his sixth start of the season.
Zegras, Troy Terry, Isac Lundestrom and Adam Henrique scored for Anaheim. Terry's goal extended his point streak to a career-best seven games (4-5=9). Bo Groulx also recorded his first career NHL point and assist.
Vegas opened the scoring three minutes after the opening faceoff as Reilly Smith snuck behind the Ducks defense for a breakaway. Gibson denied Smith's initial bid but the rebound carromed right back to the Vegas forward, who slipped it by Gibson's outstretched right pad to give the Knights the early lead.
The Knights peppered the Ducks' net throughout the first period, but only led by a goal after 20 minutes thanks to a brilliant performance by Gibson, who stopped 20-of-21 shots to keep Anaheim in it early.
"That was one of the most dominant periods of any goalie I've ever seen," Zegras said of Gibson. "Everyone in that locker room has the utmost respect for him and what he does."
"Gibby put on a performance like I haven't seen in a while," Eakins added. "That was some of the best hockey I've ever seen him play and I think that rallied the guys."