The first two episodes were apparently so bad that they were never shown.
Serial criminal John Cooper was caught and convicted of murder after appearing on the show as a contestant in May 1989. A member of the pubic noticed how much he resembled a photo-fit of a man wanted by police in connection with the murder and he was eventually tracked down and convicted (after a lengthy legal process) of a string of rapes and burglaries as well as the murders. He is still in prison as of 2024. Since this revelation, the episode featuring Cooper has never been repeated.
37 episodes of this series, ranging from 1981 to 1987, are missing from the archives. The two pilots are also missing.
Only once in the series did none of the contestants decide to gamble for the star prize, leaving the episode with no ending. To prevent this happening again, the producers decided that if the winning or runner-up couple chose not to gamble,and the third couple (often with a low amount of prize money) were also unwilling to gamble, they would be secretly told they could keep their money if they gambled and lost, to guarantee the episode its climax.
The rules on the Star Prize Gamble changed about 2/3rds of the way through the show's run - the winning pair had to gamble their money won in the earlier rounds, as well as their prizes. Previously they only had to risk the prizes and were allowed to keep the money if they lost.