E-commerce giant Amazon.com (AMZN 3.81%) is gearing up for a second-quarter earnings report, slated for the evening of July 25. The company smashed its own guidance across the board in the first-quarter report three months ago. Will this report be any different?

Here are three of the most interesting details that we Amazon investors should keep in mind on Thursday evening.

1. The usual numbers

The headline metrics that should move Amazon's share prices on Friday point to roughly $61.5 billion in top-line revenues and $3.1 billion of operating income. Those are the midpoints of Amazon's official guidance, corresponding to approximately 17% year-over-year revenue growth and flattish operating profits. Of course, Amazon left the profit target wide open as usual, ranging all the way from $2.6 billion to $3.6 billion.

2. Prime Day

As a mid-July event, Amazon's Prime Day didn't affect the second quarter, as it fell into the third reporting period of this fiscal year. Still, you should expect management to spend some time and column inches on how that discount shopping even worked out.

So far, we know that Amazon sold more than 175 million items in the two-day discount spree, passing the combined item volume of last year's Black Friday and Cyber Monday combined. Amazon's own Alexa-powered devices were among the hottest-selling items here. Small and medium businesses also saw a $2 billion order swell through Amazon's third-party shopping services, which were promoted alongside the company's in-house retailing efforts.

Further detail is to be expected alongside the earnings report, setting the foundation for Amazon's third-quarter guidance.

A large tractor trailer with the Amazon Prime logo on its side.

Image source: Amazon.

3. Free one-day shipping

The Prime shipping program has been offering free two-day package deliveries for an annual fee since 2005. The company started to step it up to a free next-day shipping program in the first quarter, rolling out that upgrade across the U.S. market in June.

Color commentary on that effort will be warmly appreciated. Are customers responding to the faster shipping service with more frequent orders? Does the faster service support more impulsive buys, where the customer takes the plunge on an attractive deal or product with less preparation and price comparison? Will consumers flock to the improved Prime subscription in greater numbers and stick around for a longer period?

Are the positive effects of this upgraded program -- whatever they may be -- worth the increased costs of providing a tighter delivery schedule?

We may not see answers to all of these questions, and it may be too early for Amazon to draw final conclusions from the overnight-shipping program anyhow. Still, some high-level executive analysis would be welcome.