Not only are there traditional keys, but coins can be transformed into pink coins that will make a key appear when completely collected. (dualpixels.com)
As with lots of other Mario games, Super Mario Run scatters five pink coins in each level. (waypoint.vice.com)
Most people dislike that Mario moves automatically, but I think this makes the game more challenging - like getting pink coins or grey coins. (theguardian.com)