I'm not sure if this has been reported before, I've noticed two annoying bugs (I'm on android, german time zone UTC+1):
1. The calendar display seems to be a bit buggy with day-spanning events, like birthdays: It always shows the duration spanning two days: E.g. the birthday is on Monday then it would show "Mo-Tue" above the birthday event. The event is generated by by google calendar.
2. Today, on Sun, 28th I have no appointments, but a base training, perfectly shown under "Sun 28". However the next day, Monday 29th is shown as "Sun 28", too.
See the below picture for both bugs (german UI).