The team displayed a message to support an on-going campaign to claim sovereignty of the islands, a British Overseas Territory.
Argentina then beat Slovenia 2-0 with goals from Ricardo Alvarez and substitute Lionel Messi.
They start their Group F campaign against Bosnia-Herzegovina on 15 June.
Coach Alex Sabella chose not to risk top star Lionel Messi, Manchester City's Sergio Aguero, Napoli striker Gonzalo Higuain or Real Madrid's Angel Di Maria from the start of their final friendly before the finals in Brazil.
"We have a great group and team," said Messi. "A World Cup is very tough and we will have to fight a lot for it.
"We arrive with the right age, with most of us playing in the best leagues of Europe for years. Winning it is our target, but it will be very hard."
Argentina also face Iran and Nigeria in their qualifying group and are second favourites with most bookmakers.