The current implementation of FBPreparedStatement and FBCallableStatement are not compliant with the JDBC specification as they allow use of methods defined on java.sql.Statement that are explicitly marked with "Note:This method cannot be called on a PreparedStatement or CallableStatement." in the Javadoc (this was added with JDBC 4.0). These are mostly the methods that accept a string with a query.
These methods should be modified to throw an SQLException in FBPreparedStatement and/or FBCallableStatement. It would probably also be a good idea to review the current class hierarchy and see if it is actually sensible that FBPreparedStatement extends FBStatement and that FBCallableStatement extends FBPreparedStatement.
Example of problem: http://stackoverflow.com/q/13754898/466862