Big Brother experienced a third security breach last night even after executives reinforced safeguards amid growing chaos inside the house.
Staff had installed a net across the garden in an effort to block fans from sending items from outside.
Nevertheless, a fan known as "Tennis the Menace" succeeded in getting a batch of balls into the area.
This marks the third occasion the local individual, who has no ties to production, has pulled off the stunt.
He bypassed the net by swapping standard Slazenger balls for smaller mini versions.
The Sun was able to disclose two of the notes that made it into the garden.
One read: "They're all whispering about Philip." The other said: "The mask is slipping."
It remains unclear whether any housemates saw the messages, as crew members sealed the house immediately after detecting the intrusion.
A source commented, "Fans loved the tennis balls at first and thought it was a revival of the good old days of Big Brother when the nation was captivated.
"It's become clear now, though, that the balls are actually affecting show flow for example earlier messages about Rochelle and Philip being the favourites clearly had a part in 'the hierarchy' being established.
"Whether that's a good or a bad thing is up for debate.
"But certainly bosses were left fuming that their extra measures to avoid this outside interference had failed."
It is not known which, if any, housemates read the notes, though some were present in the garden when the balls landed.
