I just ran across a bug... if two words are anagrams of each other and both are given as options then you can (I did) pick the "wrong" one... I realise the chances are small but they might well be larger due to the way you pick the words and it happened to me (though the RNGod doesn't like me especially so...)
Just got "trail" and "trial" and picked the wrong fifty/fifty... happened two other times but I didn't spot the second of the anagrams... (I had already confirmed the word I chose had exactly the correct letters) out of five games which gives a rate of 20% of lives lost due to this bug and about 3% of problems posed - I got to an average of about 20 puzzles solved in each run.
Great game though - still play regularly! :)