Problem 1:
On s. 15, an (unshown) controller is PULLING data from "3: Login Page"
(this is a bit unclear on the slide, but "4: validateLoginInfo"
is an INCOMING arrow for "3: Login Page".) And the same (unshown)
controller is invoking "5: display". On s. 16, however, the login data is
being PUSHED to the controller which makes much more sense for a web-based
setting (which happens to be the case here).

Problem 2:
On s. 15, "7: Customer presses Reminder Word Button ()" -- this is not a
good way to name something that will later become a method in some class.
The right way to do is shown on s. 16.

Problem 3:
On s. 15, "11: displayErrorAndPrompt", "12: displayErrorAndPrompt". It
does not make sense to call this method twice in a row. Even if these two
invocations are meant to do different things (note that this is
technically doable e.g. when DisplayErrorAndPrompt is a stateful mehtod),
this is not a good way to do it in a sequence diagram -- the
error-and-prompt functionality should be localized to a single method at
least as far as the sequence diagram is concerned.

Also note that neither sequence diagram is complete.