Jose Villareal's goal, originally ruled offside, enabled the Los Angeles Galaxy to rally for a 2-1 victory at StubHub Center in front of an announced crowd of 20,093 that included David Beckham and Victoria's Steve Nash.
Camilo scored his league-leading 13th goal for the Whitecaps (9-6-5), who fell into a four-way tie for third place in Major League Soccer's Western Conference with the Galaxy (10-8-3), Dallas and Colorado.
Vancouver held a 1-0 lead before Villareal tapped a two-yard shot past goalkeeper Brad Knighton in the 29th minute. Juninho began the play with a 34-yard free kick that Galaxy defender Omar Gonzalez headed toward the net.
Lineman Jeremy Hanson raised his flag to indicate Villareal as offside. But after conferring with referee Chris Penso, Villareal received credit for the goal.
The Whitecaps' players immediately surrounded Hanson to protest, and Vancouver coach Martin Rennie argued with fourth official Juan Guzman.
"I haven't seen that before," Rennie said of the decision. "If you're in doubt, usually, you don't give a goal, and there was obviously some doubt."
Galaxy forward Gyasi Zardes, stationed behind Villareal, was in position to head the ball into the goal. Had Zardes touched the ball, Villareal would have been offside. But a replay showed Zardes barely missing his attempted header.
"It was a key moment in the game," Rennie said. "But we're not blaming the referee. We have to be good enough to overcome that."
Zardes put Los Angeles ahead in the 57th minute. Zardes retrieved Todd Dunivant's long ball along the left flank near the end line, eluded defender Brad Rusin and struck a seven-yard shot inside the far post.
The Whitecaps' best chance to tie came in the 73rd minute, after Kekuta Manneh made a steal and passed to Kenny Miller. But Miller's nine-yard shot hit goalkeeper Carlo Cudicini's right ankle.
"I don't think we played as well in the second half as we would have liked to," Knighton said. "We were too open, at times. A team like L.A. is going to take advantage of that, and they sure did."
Camilo scored his 10th goal in the past eight games in the 19th minute. Russell Teibert deflected Lee Young-Pyo's cross from the right flank to an unmarked Camilo, who converted from 17 yards.
That goal kept Camilo one ahead of Chicago's Mike Magee in the race for the goal-scoring championship.
Los Angeles played without Landon Donovan and Robbie Keane. Donovan is with the United States' Gold Cup team and Keane injured his hip flexor muscle July 13 against Portland.