Google calendar has an option to automatically create calendar entries based on certain emails you receive in gmail, restaurant or airline reservations etc. While this can be useful, it can also lead to errant calendar entries. You can follow the steps below to disable this functionality.
1) Open Google Calendar, then click on the settings 'gear' icon.
2) From the dropdown select 'Settings'
3) Scroll down to the section called "Events from Gmail:" and uncheck the box for "Add automatically".
4) You will be prompted with a confirmation box that informs you that making this change will remove any entries that have previously been added automatically (this will not affect normally calendar entries).
5) Verify that the checkbox is now unchecked.
6) Scroll to the bottom of the page and click "Save" to save your changes. Calendar entries should no longer be auto created based off of gmail email content.