If he wee's while he poos teach him to hold his penis down with a finger so it hits the loo not the floor.

Afraid boys just make a mess sometimes, I'd very much like to know how my 4 year old gets it under the cat litter tray!

Thanks for the advice ellie. There have not been anymore accidents.

As for the cat litter tray problem, my female cat will stand up while weeing and it sprays the wall and then runs under the cat litter tray. I have put newspaper under the litter tray.