The report highlights the challenges faced by accounting departments in calculating the total cost of a trip, with 64% of them stating that they do not have the necessary data. The top 5 big data challenges include consolidating all data through Multi-Source Data Consolidation, visualizing and analyzing data better, moving market share, negotiating new agreements, managing hidden spend, addressing compliance issues, and getting answers to questions that were not previously considered. The report suggests that using consolidated data can help overcome these challenges and provide more accurate insights into the total spend picture.