i had some issues with a few kits, some are easy, some take some work, some are a pain. i had a hasagawa 1/48th scale FW-190A-8 and that one required some work to get them to close, i got the Revell P-61 Black widow and i had to do some trimming to the flaps to get them closed. as for the Revell B-19 Superfortress, that is a pain to have the gears closed, i had to basically glue the doors shut trim them just right to fit, and have them healed in place just right... i wish they had peaces for the doors to be closed, but i had to do some custom fitting.
i also did a build for the Revell B-25 Mitchel, and the little landing gear doors, i never got the stinking things to stay, but the Revell P-51, with just a teeny bit of trimming they just fall in place, a tad bit of glue and they look really nice.
what really sucks is when you want to have the landing gears open and they break, then you have to mess with them to fix them.