Overnight, Epic Games accidentally enabled cross-play between Xbox One and PlayStation 4 in co-op sandbox survival game Fortnite.
The feature was only enabled briefly, but it was active long enough for Reddit users to puzzle over it.
Epic called the enabling an error.
"We had a configuration issue and it has now been corrected," an Epic spokesperson told Eurogamer.
Public calls for cross-play between Xbox One and PlayStation 4 have been loud from both players and developers this year, with many struggling to understand how it is that Nintendo can allow cross-play with Xbox yet Sony won't.
In June, PlayStation global sales and marketing head Jim Ryan said money and security were the main reasons why Sony isn't interested.
"It's a commercial discussion between ourselves and other stakeholders," he said.
"We have a contract with the people who go online with us, that we look after them and they are within the PlayStation curated universe. Exposing what in many cases are children to external influences we have no ability to manage or look after, it's something we have to think about very carefully."
Neither Xbox nor Rocket League developer Psyonix were convinced.
"I just really found the whole discussion around safety in our game, and that somehow we wouldn't take that as a top priority... Frankly, through the parental controls on Xbox Live and everything we've done, we've shown that's very important to us as a platform," said Xbox boss Phil Spencer.
Psyonix publishing boss Jeremy Dunham added, "From our perspective, if PlayStation already allows cross-network with PC, which is the least regulated of any of the partners, then in theory, having Xbox and Switch in there should be fine."
Other developers then claimed that enabling cross-play would be trivially easy, including Ark: Survival Evolved studio Wildcard, which stated it would only take a few days to get it up and running.