Probably just the usual naughty tricks he gets up to, mind tricks to make life slightly easier, etc. If anyone read the TPM novel, he actually steals a power source from Watto to get the pod running. Probably stuff like that which, whilst for a good cause, makes the Jedi seem less like calm transcendent beings, and more like people who take sides too easily. Look at the scorn in the remark towards Padme, regarding her trusting his judgement. She's 14, you wouldn't see Alec Guinness' Obi Wan coming out with that.