When a mobile device is used to enter time a mobile enhanced timesheet can be used. This enhanced view makes it easier to enter time on any mobile device. The user does have the ability to return to the original non-enhanced view by clicking a link located on the top of each page.
If you are an administrator, there is a checkbox in the settings area called "Allow mobile timesheet access".
The below shows an example of the mobile timesheet enhanced view. Notice the link on the top which allows the user to return to the original non-enhanced timesheet view.