Mixed case is not an issue for oracle when it comes to SQL, SQL is NOT case sensitive.
What version of crystal are you using. ?
Are the database schemas from Access and Oracle identical?
Are you doing a lot of date comparisons in your report queries? Access and Oracle do not handle dates in the same way (if you are comparing dates with a date string)
Are you passing crystal recordsets from VB
or is crystal getting the data right from the database through its own queries (In other words, where is the data access happening)?
I have had problems simply changing the table name in a Crystal report I imagine changing the database is going to cause you several headaches.