Tech giant Google (click ticker for report: GOOG) accidentally reported weaker than expected third quarter earnings today. Printing firm RR Donnelly (click ticker for report: RRD) mistakenly filed Google’s third quarter earnings just after noon eastern time, leading to some erratic trading in shares of the search giant. Regardless, the report revealed that revenue surged 45% year-over-year to $14.1 billion, boosted by the firm’s acquisition of Motorola Mobility (a bit lighter than anticipated). Earnings per share fell 7% year-over-year to $9.03, much worse than consensus expectations.

Paid clicks surged 33% year-over-year and 6% sequentially, driven by increasing mobile ad share, in our view. However, cost-per-click fell significantly, down 15% year-over-year, while traffic acquisition costs grew to 26% of revenue from 24% of revenue during the third quarter of 2011. Again, we suspect the migration to mobile may be causing more total clicks, but mobile ads are far less valuable than desktop ads. Though this could change eventually, especially when consumers become more comfortable with mobile shopping, the smaller and less effective ads command a considerable discount to traditional advertising.

Motorola revenues came in at $2.58 billion, but posted a non-GAAP loss of $151 million. We’re not exactly sure what Google has in mind for this hardware segment, but we suspect the company is laying the foundation to build its own hardware. In the interim, we expect the segment to lose money, but after considering Google’s cash flow generation capability, we don’t think it will be very material. The firm still posted $4 billion in operating cash flow during the third quarter and $3.13 billion in free cash flow. We plan to provide more color following the analyst call as new details come to light.