Security in 2.5 is much better than previous versions, however it takes a little more time. You have to set the entity access per module per entity. You can use the "set all to read" button in order to set all access rights for all selected user roles per entity to read. For now you have to do it for each entity, which might take some time. Setting security for a batch of entities would be a great feature from my point of view.
I'm guessing these errors are related to these roles having access to several forms with entities that they don't have access to. Either don't show these forms to these roles or configure security so they can see the fields in the entities that are shown.