Star Wars: The Phantom Menace (Film)

Young Anakin Skywalker (later known as Darth Vader), still aged 6 in his Tatooine home world, participates in an illegal, dangerous sport — pod racing. Each racer rides a small cockpit craft pulled by (typically) two oversized thrust engines, across a dramatic landscape of mesas, canyons and caves, at an average speed of some 850 mph...

Just before the start of the race, the Boonta Eve Classic race of 32 BBY, the flags of each racer (or of his sponsor) are shown, paraded across the start line by one of each racer's ground crew — Anakin's flagholder being the robot C3PO (Cee Threepio).

The full list of podracers in the Boonta Classic edition featured in The Phantom Menace seems to be of 25, compiled from several sources. I do not know whether all of them were visible in the final cut of the movie, though.
António Martins-Tuválkin, 21 April 2001

the Wookieepedia page mentioned here, does now include the flag designs! These come from the _The Official Star Wars Fact File_ and can be regarded as canonical, although they are still wordlessly added as an afterthought to the page, and individual racer's pages do not include them (yet).

Here, we can see some common features between some sponsors' flags and their pods' liveries.

Here we learn that Podracers bore Huttese writing, as well as their displays, and therefore we can speculate that at least some of the symbols on the flags are Huttese-written.
António Martins-Tuválkin, 29 August 2008

This flag is just like those of racers Gasgano, Neva Kee, Ebe Endocott, Boles Roor (with 3 streamers), and Wan Sandage (streamers at top and bottom).

Dud Bolt's craft is painted in the same light green as so many others, but it shows proeminent light blue rudders and red exhaustors, so that it more or less matches the colors of his flag. (See here and here.)

Gasgano is a Vulptereen podracer pilot; he actually works for Sebulba, taking down other racers so his boss can win more easily. In Boonta Eve Classic of 32 BBY he crashed during the third lap. More information at the Wookiepedia.
António Martins-Tuválkin, 4 September 2009

Ebe Endocott's sponsor flag consists of a long (1:2 or longer) plain rectangular cloth with 2 triangular streamers (about 1:10) above it all fixed to the same staff — just like racers Dud Bolt, Gasgano, Neva Kee and (with 3 streamers) Boles Roor. The main flag is light blue and the streamers, two of them, are red.

Ebe E. Endocott is a Triffian podracer; in the Boonta Eve Classic of 32 BBY he finished 4th. < http://starwars.wikia.com/wiki/Ebe_E._Endocott > for more information.
António Martins-Tuválkin, 31 August 2008

I'm afraid that the main cloth of this flag may be green instead. Truth is that the images here scanned from The Official Star Wars Fact File use remarkably off-key hues and comparing these depictions with the few of the actual flags seen on set yield disparate results. More on this later.

This flag is just like those of racers Dud Bolt, Neva Kee, Ebe Endocott, Boles Roor (with 3 streamers), and Wan Sandage (streamers at top and bottom).

Gasgano's craft is painted light green with some parts red and orange, which more or less matches the colors of his flag. (See here and here.)

Gasgano is a male Xexto podracer; he finished second in the Boonta Eve Classic of 32 BBY. More information at the Wookiepedia.
António Martins-Tuválkin, 3 September 2009

Neva Kee's sponsor flag consists of a long (1:2 or longer) plain rectangular cloth with 2 triangular streamers (about 1:10) above it all fixed to the same staff just like racers Dud Bolt, Gasgano, Ebe Endocott, Boles Roor (with 3 streamers), and Wan Sandage (streamers at top and bottom). The main flag is medium blue and the streamers, two of them, are dark blue (topmost) and white.

Neva Kee's craft is painted in shades of blue, which roughly matches the colors of his flag. (see here)

Neva Kee is a Xamster podracer; in the Boonta Eve Classic of 32 BBY he disappeared during the 2nd lap, while driving an unusual craft with the pod (cockpit) located at the front end of the engines. More information at the Wookiepedia.
António Martins-Tuválkin, 31 August 2008

Wan Sandage's sponsor flag consists of a long (1:2 or longer) plain rectangular cloth with 2 triangular streamers (about 1:10), one above and the other below the main cloth, fixed to the same staff quite like racers with streamers at top only, like Neva Kee, Dud Bolt, Gasgano, Ebe Endocott, and Boles Roor (with 3 streamers). The main flag is yellow and the streamers are white.

Wan Sandage's craft is painted in shades pale green and pale yellow, which seems unrelated to the colors of his flag. (See here.)

Wan Sandage is a male Devlikk podracer (looks like a cartoon fox); in the Boonta Eve Classic of 32 BBY he hired Aldar Beedo to eliminate Sebulba but end up crashing in the third lap.
António Martins-Tuválkin, 2 September 2008