The fans charged through a security checkpoint before smashing down a glass door, witnesses said, and invading the working room.
They ran around the journalists' workplace looking for access to the stadium, before police were called.
"They stormed the gate and ran into the stadium. We stopped them," security guard Diego Guilherme de Souza Goncalves told Reuters.
The spectators were being held seated on the floor, while police took them away in groups.
"A group of individuals without tickets violently forced entry into the stadium, breaking fences and overrunning security," world soccer's governing body FIFA said.
"They were contained by the security and did not make it to the seats. The situation was brought under control quickly and at least 85 intruders were detained according to the military police of Rio de Janeiro.
"The organisers of the FIFA World Cup condemn these acts of violence and we will communicate further information and measures to be taken in due course."
The Brazilian federal police later on Wednesday said that it will give three days for those fans to leave the country or face deportation.
At least one Chilean fan, a woman, was injured and taken outside in a wheelchair.
There had been a lively atmosphere around the Maracana earlier on Wednesday, with thousands of red-shirted fans singing, chanting and dancing in the streets.
Chileans fans, already in high spirits before the game, went into a frenzy after their team defeated Spain 2-0, eliminating the holders from the World Cup.
Chile, who won their opening group match against Australia 3-1, secured a berth in the last 16. The South American team will play the Netherlands on June 23 in its last Group B game.
(Additional reporting by Alonso Soto; Simon Evans, Bill Schomberg and Benjamin Walsh; Editing by Ed Osmond/Alan Baldwin)
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