Your company's marketing efforts are not confined to your marketing department. Any interaction with consumers should be considered part of your marketing, whether that's your customer service, product packaging or even your order forms. Marketing is anything that affects a consumer's perception of you.
When you think of "marketing collateral" you shouldn't just be thinking of your flyers and brochures; you should be thinking of your employees, your operations, and most importantly, your overall customer experience. Most companies tend to treat operations and sales/marketing as two separate entities, often causing a rift between the two or at least a different set of priorities. This is a serious mistake. A marketing campaign may attract a ton of new business, but it doesn't do much good if operations can't keep up with demand, or if the product falls apart when the customer receives it, or if the instructions are too confusing to understand, or if the customer is put on hold for a half hour when they call with a question. Each of these aspects of your business contribute to your customers' perception of you, thus making each one part of your overall marketing message. Let's call these non-traditional factors "peripheral marketing". Even aspects of your business that are primarily behind-the-scenes, such as supply chain management or your internal processes, may indirectly impact your customers' experience and therefore be part of your peripheral marketing.