It sounds like you have Remember The Milk for Google Calendar added, which just embeds a small RTM page behind each checkmark. This calendar isn't viewable on mobile browsers or other calendars that synchronize with Google Calendar.

You may want to subscribe to your iCalendar in Google Calendar and then have that one synchronize. Instructions for doing so are on our site.

Keep in mind that you can hide that iCalendar from Google Calendar but still have it available to you on your phone.