Details from your experience letter will be drafted in an e-mail and sent to your previous employer's HR contact or at the most your Reporting Manager, if you have provided his/ her contact details. Mostly, such verification e-mails lands up with HR only - so not to worry on anything.
Due to legal and reputation loss ramifications - Employer's only verify the Tenure, Designation/ Career Level, Location and Department ONLY. They will not even write a single word more than that. Even few Employers just reply with a 'Yes', 'OK', 'Confirmed' - when your new Employer sends them an e-mail containing your records. That's all.