If you do not remember any metal detectors at the 1984 Los Angeles Olympics, you are right. There weren't any. But they were in use at Tuesday night's Mass at the Coliseum and partially responsible for all those long lines and delays for spectators.
The Secret Service had tried to institute this sort of security check for the Olympics opening ceremonies at the Coliseum but was foiled by the Los Angeles Olympic Organizing Committee and the L.A. Police Department, which argued that the use of metal detectors would lead to long delays. When a few detectors were used in some VIP sections closest to where President Reagan was scheduled to sit, they created such a crush in certain tunnels that they had to be scrapped.
Unlike Reagan, who appeared publicly only in a closed steel-reinforced box, Pope John Paul II was in the open for hours at the Mass. The Pope's greater exposure was enough to persuade security authorities that the use of metal detectors and other checks throughout the stadium was necessary no matter how much they inconvenienced spectators.