Right after the bat I sent the email, I had a reader pinged me that United Explorer link is going back to the 40k offer, which means 1^st purchase is 25k, I’d like to point out that
1.   The links expire very often, you need to act quick
2.   Save the screenshoot to prove to Chase if needed
3. You can still apply for the card and SEND a SECURE message to Chase after you get the card and they normally honor the 50k offer if you show them the screenshot, like I did for the $50 credit I missed when I applied the card.
  
Thank you for your recent inquiry on your United
MileagePlus credit card account.

We have reviewed the application that you completed and
the enrollment offer attached to that application states
you will receive 50,000 enrollment miles after your first
purchase and the first year annual fee waiver. In
addition, you can earn 10,000 bonus miles if you spend
$25,000 in purchases in any calendar year (January through
December). Once all of the above have been met you will
have received a total of 60,000 miles.

As you requested, we have applied a $50.00 statement
credit to your account. You will see this adjustment on
your next billing statement.

If you have any further questions, please reply using the
Secure Message Center.
4. You can also go to the below post to find out the working link, normally, if you have United Mileage Plus and have a few miles on your account, you may just log on to your account to see the offer is 50k(60k) or not.
http://millionmilesecrets.com/2012/01/05/chase-united-60000-2/