Another bug I've found is (I think) on 4-3, where you have a chest with wingsmIf you push the crate to the left after the treasure chest position but before making it appear, chest is unreachable, you can't move to its middle, really weird (that's what happen when we try to find all secrets, got from many of the screens,
Great to have this feedback!!! Yes, there is a flaw in the design there. Appearing chests and creates don't go well together. I've been blind to this one. Thanks.
2-2 is one I've tried quite a few times and yet did not discover all secrets, congrats 
This is cool to hear. I wonder if anyone has found all bonus rooms.
Found two more issues, one is in the same crate on 4-3,if you push it two spaces to the right and die, it will respaw in the original position and a copy of it in the position where you left. The respawned one is impossible to move while you can move the copy crate 
Second is really minor, using the joystick (did not try with the keyboard), when you get something from a chest, if some direction is pressed and you push A button, button is not recognized and the screen after the chest showing its contents doesn't go away, it only works if A is pressed and no direction is held...
Regarding the secrets, at least in our group no one found all secrets yet, still looking for it on two stages 
Found two more issues, one is in the same crate on 4-3,if you push it two spaces to the right and die, it will respaw in the original position and a copy of it in the position where you left. The respawned one is impossible to move while you can move the copy crate
Awesome!!! Great catch! But - I don't think the specific movement matters. I have not been able to reproduce this unless I am in the midst of pushing the crate. And - this makes sense. The crate is pushed 16 in chunks of pixels, and what happens here is that the movement is aborted midway - and "movement cleanup" isn't carried out => Bug => me fix asap!
Second is really minor, using the joystick (did not try with the keyboard), when you get something from a chest, if some direction is pressed and you push A button, button is not recognized and the screen after the chest showing its contents doesn't go away, it only works if A is pressed and no direction is held...
Yes, to progress by pressing A, no direction keys can be pressed at the same time -- I can prolly tweak this thingy.
Thanks!
@Bengalack
Is it possible to find all secrets on 2-2 on the current version? I've really jumped every bit of space I could and tried almost anything except for trying crates on exotic configurations (tried pushing and jumping on top on every possible square though) near the two chests with pouches and could not get a found all secrets there... Seems to me I'm missing on a Mushroom as I've seen one of your videos where you zap through rolling rocks invulnerable in that stage, don't want the secret to be revealed though, just a confirmation that in the current version it is possible to find all secrets on 2-2 and receive the 5000 bonus... 
By the way, if finishing the game finding all secrets, does the ending change in any form?
Naturally I don't know which ones you have seen, but there's a sneaky one in 2-2. Took me a while to figure out, and once it has been seen, it can't be unseen. 
@Bengalack
Is it possible to find all secrets on 2-2 on the current version? I've really jumped every bit of space I could and tried almost anything except for trying crates on exotic configurations (tried pushing and jumping on top on every possible square though) near the two chests with pouches and could not get a found all secrets there... Seems to me I'm missing on a Mushroom as I've seen one of your videos where you zap through rolling rocks invulnerable in that stage, don't want the secret to be revealed though, just a confirmation that in the current version it is possible to find all secrets on 2-2 and receive the 5000 bonus...
Yes, absolutely. Wolf is right. It's just that the entry might be a bit different that the ones you are used to.
As for the mushroom - it was used in the video to demonstrate the power-up. In the end, that power-up was removed from the caves-level. So - you only missing out on the bonus-room, not the mushroom.
By the way, if finishing the game finding all secrets, does the ending change in any form?
If we are talking about the bonus-rooms, it's a challenge to the completionists and something that can give you the highest possible score. I could possibly have made something special from this at the end of the game, but I didn't in this game or this version at least Good idea though. Lemme use this in my next game
Or you can implement it on physical version, if there is e enough room left as a bonus for physical buyers...
It would be quite nice 
@Bengalack
Is it possible to find all secrets on 2-2 on the current version? I've really jumped every bit of space I could and tried almost anything except for trying crates on exotic configurations (tried pushing and jumping on top on every possible square though) near the two chests with pouches and could not get a found all secrets there... Seems to me I'm missing on a Mushroom as I've seen one of your videos where you zap through rolling rocks invulnerable in that stage, don't want the secret to be revealed though, just a confirmation that in the current version it is possible to find all secrets on 2-2 and receive the 5000 bonus...
Yes, absolutely. Wolf is right. It's just that the entry might be a bit different that the ones you are used to.
As for the mushroom - it was used in the video to demonstrate the power-up. In the end, that power-up was removed from the caves-level. So - you only missing out on the bonus-room, not the mushroom.
By the way, if finishing the game finding all secrets, does the ending change in any form?
If we are talking about the bonus-rooms, it's a challenge to the completionists and something that can give you the highest possible score. I could possibly have made something special from this at the end of the game, but I didn't in this game or this version at least Good idea though. Lemme use this in my next game
Could find it today, after Wolf told that you couldn't unsee it after seeing it, it was enough to help me find it out, congrats, very well hidden still fair game 