For some really stupid answers from flash, check out this discussion: A thread on Mathematics
A very amusing thing you can do: In AI Studio, have Gemini 1.5 flash answer a question, like this one:
We are given the sequence of numbers 2, 5, 10, 17. Which of the following 3 options is the correct continuation for this sequence: (a) 22, (b) 26 or (c) 34?
Then switch the selector to 1.5 Pro and repeat the question. Gemini 1.5 Pro starts out by profusely apologizing for the error in the previous response (the poor thing has been tricked into thinking it generated the answer), and then proceeds to answer the question correctly.
Flash is good for speed, not really good for high quality answers.