Here's one that really did happen once. I was watching BBC1 one afternoon, and there was a game on called XYZ. This was about 1:45-150pm. At the same time, on BBC2 were schools programmes. At one point on nBBC1, the contestant asked for R, and the next thing, it comes up top left corner "replay" and footage of someone hitting symbals.
What had happened was, for some reason, BBC2's output was broadcast on BBC1 for a few seconds.
BTW, no apology given at the end of the programme for the output error.
Conceivably that could have been a screw up at the transmitter site or the regional centre rather than anything pres would know about in order to apologise.
There were still schools programmes on so it must have been a while back. When the BBC still did split digital and analogue presentation there was a switch-over in the afternoon and late at night when BBC1 and 2 pres suites were switched into and out of line.
If it was during that time (1998-2002ish) then it sounds like it was that where the issue occurred
Did anyone capture the moment in todays British Grand Prix coverage where the BBC's David Coulthard and Sky's Martin Brundle met on the grid either from BBC or Sky, ideally both. Brundle seemed more willing to talk than Coulthard and in fact the BBC cameraman got left behind with a car coming between him and his presenter as Coulthard tried to get away from the situation.
In other news, another forum member, who is a little shy, mentioned to me that the BBC can be seen in the background of the Wimbledon.com coverage, or was it the other way around. I forget.
BBC 1 and Channel 4 both broadcast the first series of Celebrity Big Brother in 2001 for Comic Relief. While Channel 4 aired the main Highlight Shows, BBC 1 aired 10 minute recaps and the live Final.